Estevam A Bonfante

Publications of Estevam A Bonfante

• Reliability and failure modes of internal conical dental implant connections.

  Authors: Amilcar C Freitas-Júnior, Erika O Almeida, Estevam A Bonfante, Nelson R F A Silva, Paulo G Coelho

  Clinical oral implants research. 03/2012;

  OBJECTIVE: Biological and mechanical implant-abutment connection complications and failures are still present in clinical practice, frequently compromising oral function. The purpose of this studyOBJECTIVE: Biological and mechanical implant-abutment connection complications and failures are still present in clinical practice, frequently compromising oral function. The purpose of this study was to evaluate the reliability and failure modes of anterior single-unit restorations in internal conical interface (ICI) implants using step-stress accelerated life testing (SSALT). MATERIALS AND METHODS: Forty-two ICI implants were distributed in two groups (n = 21 each): group AT-OsseoSpeed(™) TX (Astra Tech, Waltham, MA, USA); group SV-Duocon System Line, Morse Taper (Signo Vinces Ltda., Campo Largo, PR, Brazil). The corresponding abutments were screwed to the implants and standardized maxillary central incisor metal crowns were cemented and subjected to SSALT in water. Use-level probability Weibull curves and reliability for a mission of 50,000 cycles at 200 N were calculated. Differences between groups were assessed by Kruskal-Wallis along with Bonferroni's post-hoc tests. Polarized-light and scanning electron microscopes were used for failure analyses. RESULTS: The Beta (β) value derived from use level probability Weibull calculation was 1.62 (1.01-2.58) for group AT and 2.56 (1.76-3.74) for group SV, indicating that fatigue was an accelerating factor for failure of both groups. The reliability for group AT was 0.95 and for group SV was 0.88. Kruskal-Wallis along with Bonferroni's post-hoc tests showed no significant difference between the groups tested (P > 0.27). In all specimens of both groups, the chief failure mode was abutment fracture at the conical joint region and screw fracture at neck's region. CONCLUSIONS: Reliability was not different between investigated ICI connections supporting maxillary incisor crowns. Failure modes were similar.

• Effect of microthread presence and restoration design (screw versus cemented) in dental implant reliability and failure modes.

  Authors: Erika O Almeida, Amilcar C Freitas Júnior, Estevam A Bonfante, Eduardo Passos Rocha, Nelson R F A Silva, Paulo G Coelho

  Clinical oral implants research. 03/2012;

  OBJECTIVES: This study evaluated the reliability and failure modes of implants with a microthreaded or smooth design at the crestal region, restored with screwed or cemented crowns. The postulatedOBJECTIVES: This study evaluated the reliability and failure modes of implants with a microthreaded or smooth design at the crestal region, restored with screwed or cemented crowns. The postulated null hypothesis was that the presence of microthreads in the implant cervical region would not result in different reliability and strength to failure than smooth design, regardless of fixation method, when subjected to step-stress accelerated life-testing (SSALT) in water. MATERIALS AND METHODS: Eighty four dental implants (3.3 × 10 mm) were divided into four groups (n = 21) according to implant macrogeometric design at the crestal region and crown fixation method: Microthreads Screwed (MS); Smooth Screwed (SS); Microthreads Cemented (MC), and Smooth Cemented (SC). The abutments were torqued to the implants and standardized maxillary central incisor metallic crowns were cemented (MC, SC) or screwed (MS, SS) and subjected to SSALT in water. The probability of failure versus cycles (90% two-sided confidence intervals) was calculated and plotted using a power law relationship for damage accumulation. Reliability for a mission of 50,000 cycles at 150 N (90% 2-sided confidence intervals) was calculated. Differences between final failure loads during fatigue for each group were assessed by Kruskal-Wallis along with Benferroni's post hoc tests. Polarized-light and scanning electron microscopes were used for failure analyses. RESULTS: The Beta (β) value (confidence interval range) derived from use level probability Weibull calculation of 1.30 (0.76-2.22), 1.17 (0.70-1.96), 1.12 (0.71-1.76), and 0.52 (0.30-0.89) for groups MC, SC, MS, and SS respectively, indicated that fatigue was an accelerating factor for all groups, except for SS. The calculated reliability was higher for SC (99%) compared to MC (87%). No difference was observed between screwed restorations (MS - 29%, SS - 43%). Failure involved abutment screw fracture for all groups. The cemented groups (MC, SC) presented more abutment and implant fractures. Significantly higher load to fracture values were observed for SC and MC relative to MS and SS (P < 0.001). CONCLUSION: Since reliability and strength to failure was higher for SC than for MC, our postulated null hypothesis was rejected.

• Fatigue reliability of 3 single-unit implant-abutment designs.

  Authors: Leandro M Martins, Estevam A Bonfante, Ricardo A Zavanelli, Amilcar C Freitas, Nelson R F A Silva, Leonard Marotta, Paulo G Coelho

  Implant dentistry. 02/2012; 21(1):67-71.

  Because the mechanical behavior of the implant-abutment system is critical for the longevity of implant-supported reconstructions, this study evaluated the fatigue reliability of differentBecause the mechanical behavior of the implant-abutment system is critical for the longevity of implant-supported reconstructions, this study evaluated the fatigue reliability of different implant-abutment systems used as single-unit crowns and their failure modes. Sixty-three Ti-6Al-4V implants were divided in 3 groups: Replace Select (RS); IC-IMP Osseotite; and Unitite were restored with their respective abutments. Anatomically correct central incisor metal crowns were cemented and subjected to separate single load to failure tests and step-stress accelerated life testing (n = 18). A master Weibull curve and reliability for a mission of 50,000 cycles at 200 N were calculated. Polarized-light and scanning electron microscopes were used for failure analyses. The load at failure mean values during step-stress accelerated life testing were 348.14 N for RS, 324.07 N for Osseotite, and 321.29 N for the Unitite systems. No differences in reliability levels were detected between systems, and only the RS system mechanical failures were shown to be accelerated by damage accumulation. Failure modes differed between systems. The 3 evaluated systems did not present significantly different reliability; however, failure modes were different.

• Evaluation of surface roughness as a function of multiple blasting processing variables.

  Authors: Guilherme B Valverde, Ryo Jimbo, Hellen S Teixeira, Estevam A Bonfante, Malvin N Janal, Paulo G Coelho

  Clinical oral implants research. 12/2011;

  OBJECTIVES: This study evaluated the effect of implant surface blasting variables, such as blasting media size, velocity, and surface coverage and their two- and three-way interaction in surfaceOBJECTIVES: This study evaluated the effect of implant surface blasting variables, such as blasting media size, velocity, and surface coverage and their two- and three-way interaction in surface roughness parameters. MATERIAL AND METHODS: Machined, grade IV titanium-alloy implants (n = 180) had their surfaces treated by a combination of 36 different blasting protocols according to the following variables: aluminum oxide blasting media particle size (50, 100, and 150 μm); velocity (75, 100, 125, and 150 m/s), and surface coverage (5, 15, 25 g/in.(2) ) (n = 5 per blasting protocol). A single 0.46 inch nozzle of the blaster was pointed at the threaded area and spaced 0.050 inches away. Surface topography (n = 5 measurements per implant) was assessed by scanning electron microscopy. Roughness parameters Sa, Sq, Sdr, and Sds were evaluated by optical interferometry. A GLM statistical model evaluated the effects of blasting variables on the surface parameters, and their two- and three-way interaction (P < 0.05). Statistical inferences for Sa and Sq were performed after a log(10) transformation to correct for data skewness. RESULTS: Prior to the log(10) transformation, Sa and Sq values for all processing groups ranged from ~0.5 to ~2.6 μm and from ~0.75 to 4 μm, respectively. Statistical inferences showed that Sa, Sq, and Sdr values were significantly dependent on blasting media, velocity, and surface coverage (all P < 0.001). Media × velocity, media × coverage, and media × velocity × coverage also significantly affected Sa, Sq, and Sdr values (P < 0.002). The highest levels were obtained with 100 μm blasting media, coverage for 5 g/in.(2) , and velocity of 100 m/s. No significant differences were observed for Sds (P > 0.15). CONCLUSIONS: The blasting variables produced different surface topography features and knowledge of their interaction could be used to tailor a desired implant surface configuration.

• Alveolar buccal bone maintenance after immediate implantation with a surgical flap approach: a study in dogs.

  Authors: Paulo G Coelho, Charles Marin, Rodrigo Granato, Estevam A Bonfante, Cirilo P Lima, Sergio Oliveira, David M Dohan Ehrenfest, Mercelo Suzuki

  The International journal of periodontics & restorative dentistry. 11/2011; 31(6):e80-6.

  This study evaluated buccal bone maintenance after implantation with a surgical flap approach immediately following tooth extraction in a dog model. Mandibular premolars of six dogs were extracted,This study evaluated buccal bone maintenance after implantation with a surgical flap approach immediately following tooth extraction in a dog model. Mandibular premolars of six dogs were extracted, and threaded implants of 4-mm diameter and 8-mm length with as-machined and dual acid-etched surfaces were placed through balanced procedures in the distal root extraction sockets with a full-thickness flap design. Submerged healing was allowed for 4 weeks, and following euthanization, bone-to-implant contact and buccal and lingual bone loss were evaluated. None of the parameters evaluated were indicative of an effect of implant surface in hindering bone loss around immediately placed implants.

• The effect of different implant macrogeometries and surface treatment in early biomechanical fixation: an experimental study in dogs.

  Authors: Paulo G Coelho, Rodrigo Granato, Charles Marin, Hellen S Teixeira, Marcelo Suzuki, Guilherme B Valverde, Malvin N Janal, Tomas Lilin, Estevam A Bonfante

  Journal of the mechanical behavior of biomedical materials. 11/2011; 4(8):1974-81.

  Implant surface characterization and biomechanical testing were made to evaluate the effect of different surface treatments along with different implant bulk configurations expressed as biomechanicalImplant surface characterization and biomechanical testing were made to evaluate the effect of different surface treatments along with different implant bulk configurations expressed as biomechanical fixation at early implantation times. Three implant surfaces, namely bioactive ceramic electrodeposition (ED), alumina-blasted/acid etched (AB/AE), and resorbable blasting media (RBM) were fabricated in three implant macrogeometries (cylindrical, small chamber, and large chamber). All combinations between surface and bulk configurations were placed in the radii of beagle dogs (n=18), which were euthanized 14 and 40 days after surgery (n=9 animals per time in vivo). The implants were subjected to torque to interface fracture. Effects of time, surface, and macrogeometry on torque to interface fracture were evaluated by a GLM at 95% level of significance. The results showed a significant increase in torque as time elapsed in vivo (p<0.001), and that the ED surface presented significantly higher values compared to AB/AE and RBM (p<0.001) at both times. The small chamber only presented a significantly higher biomechanical fixation compared to other geometries at 40 days in vivo (p=0.02). Biomechanical fixation at 14 and 40 days was affected by implant surface treatment, whereas implant design only affected results at 40 days in vivo.

• Reliability and failure modes of anterior single-unit implant-supported restorations.

  Authors: Amilcar C Freitas, Estevam A Bonfante, Leandro M Martins, Nelson R F A Silva, Leonard Marotta, Paulo G Coelho

  Clinical oral implants research. 08/2011;

  PURPOSE: Failures of implant-abutment connections have been observed clinically, especially in single-tooth replacements. This study sought to evaluate the reliability and failure modes ofPURPOSE: Failures of implant-abutment connections have been observed clinically, especially in single-tooth replacements. This study sought to evaluate the reliability and failure modes of implant-supported anterior crowns restored with different implant systems. MATERIALS AND METHODS: Forty-two Ti-6Al-4V dental implants (~4 mm diameter) were used for single anterior crown replacement and divided into two groups according to tested system: (NB) Replace Select system, Nobel Biocare (n = 21); and (IL) Internal connection system, Intra-Lock International (n = 21). Proprietary abutments were screwed to the implants and anatomically correct maxillary central incisor metal crowns were cemented and subjected to step-stress-accelerated life testing in water. Use-level probability Weibull curves and reliability for a mission of 50,000 cycles at 200 N (95% 2-sided confidence intervals) were calculated. Polarized-light and scanning electron microscopes were used for failure analyses. RESULTS: The Beta values for NB and IL (2.09 and 2.05, respectively) indicated that fatigue accelerated the failure of both groups. The calculated reliability for the NB system (0.81) was lower than for the IL system (0.96), but no significant difference was observed between groups. Screw and abutment fracture was the chief failure mode in group NB, while screw fracture was most representative in specimens of group IL. CONCLUSIONS: Reliability of implant-supported maxillary central incisor crowns was not significantly different between NB and IL abutments. Failure modes differed between implant systems.

• Effect of implant-abutment connection design on reliability of crowns: regular vs. horizontal mismatched platform.

  Authors: Amilcar C Freitas Júnior, Estevam A Bonfante, Nelson R F A Silva, Leonard Marotta, Paulo G Coelho

  Clinical oral implants research. 08/2011;

  OBJECTIVES: To evaluate the reliability and failure modes of regular and horizontal mismatched platforms for implant-abutment connection varying the implant diameter. MATERIAL AND METHODS: RegularOBJECTIVES: To evaluate the reliability and failure modes of regular and horizontal mismatched platforms for implant-abutment connection varying the implant diameter. MATERIAL AND METHODS: Regular (REG, n = 21, 4.0-mm-diameter implant) and horizontal mismatched (HM, n = 21, 4.6-mm-diameter implant) platform Ti-6Al-4V implants were restored with proprietary identical Ti-6Al-4V abutments and metal crowns (cobalt-chrome, Wirobond(®) 280, BEGO, Bremen, Germany) cemented. Mechanical testing comprised step-stress accelerated-life testing, where crowns were distributed in three loading profiles for fatigue in water, producing timely and clinically relevant fractures. The probability of failure vs. cycles (95% two-sided confidence intervals) was calculated and plotted using a powerlaw relationship for damage accumulation, Weibull modulus (95% two-sided confidence intervals) and then the reliability for a mission of 50,000 cycles at 125 N load (95% two-sided confidence interval) were calculated. Fractography was performed in the scanning electron microscope. RESULTS: The β-value for group REG (β = 1.37) indicated that fatigue was a factor accelerating the failure, whereas load alone dictated the failure for group HM (β = 0.71). The Weibull parameter contour plot showed no significantly different Weibull modulus for REG (10.24) compared to HM (10.20) and characteristic strength of 162.6 and 166.8 N, respectively (P > 0.91). The calculated reliability for a mission of 50,000 cycles at 125 N load was not significantly different (0.71 for REG and 0.73 for HM). Abutment screw failure was the chief failure mode. CONCLUSIONS: Reliability was not significantly different between groups and failure modes were similar.

• Effect of implant connection and restoration design (screwed vs. cemented) in reliability and failure modes of anterior crowns.

  Authors: Amilcar C Freitas, Estevam A Bonfante, Eduardo P Rocha, Nelson R F A Silva, Leonard Marotta, Paulo G Coelho

  European journal of oral sciences. 08/2011; 119(4):323-30.

  The mechanical performance of cemented or screw-retained implant-supported crowns with an internal or external configuration is yet to be understood. This in vitro study evaluated the effect ofThe mechanical performance of cemented or screw-retained implant-supported crowns with an internal or external configuration is yet to be understood. This in vitro study evaluated the effect of screw-retained and cement-retained prostheses on internal and external implant-abutment connections. Thereby, the reliability and failure modes of crowns were investigated. Eighty-four implants (Emfils; Colosso Evolution system) were divided into four groups (n=21 each): screw-retained and internal connection (Si), screw-retained and external connection (Se), cement-retained and internal connection (Ci), and cement-retained and external connection (Ce). Ti-6Al-4V abutments were torqued (30 Ncm) to the implants, and maxillary central incisor metal crowns were torqued (30 Ncm) or cemented (Rely X Unicem; 3M-ESPE) and subjected to accelerated life-testing in water. Use-level probability Weibull curves and reliability for 50,000 cycles at 150 N were calculated. The β values for Si (1.72), Se (1.50), Ci (1.34), and Ce (1.77) groups indicated that fatigue/damage accumulation accelerated their failure. The Ci group presented the highest reliability, the Se group presented the lowest reliability, and Si and Ce groups presented intermediate reliability. Screw-retained restorations presented mainly abutment fracture. Cement-retained restorations resulted in failures of the screw in the Ce group, but implant/screw fracture in the Ci group.

• Effect of drilling technique on the early integration of plateau root form endosteal implants: an experimental study in dogs.

  Authors: Gabriela Giro, Charles Marin, Rodrigo Granato, Estevam A Bonfante, Marcelo Suzuki, Malvin N Janal, Paulo G Coelho

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 04/2011; 69(8):2158-63.

  This study tested the hypothesis that early integration of plateau root form endosseous implants is significantly affected by surgical drilling technique. Sixty-four implants were bilaterally placedThis study tested the hypothesis that early integration of plateau root form endosseous implants is significantly affected by surgical drilling technique. Sixty-four implants were bilaterally placed in the diaphysial radius of 8 beagles and remained 2 and 4 weeks in vivo. Half the implants had an alumina-blasted/acid-etched surface and the other half a surface coated with calcium phosphate. Half the implants with the 2 surface types were drilled at 50 rpm without saline irrigation and the other half were drilled at 900 rpm under abundant irrigation. After euthanasia, the implants in bone were nondecalcified and referred for histologic analysis. Bone-to-implant contact, bone area fraction occupancy, and the distance from the tip of the plateau to pristine cortical bone were measured. Statistical analyses were performed by analysis of variance at a 95% level of significance considering implant surface, time in vivo, and drilling speed as independent variables and bone-to-implant contact, bone area fraction occupancy, and distance from the tip of the plateau to pristine cortical bone as dependent variables. The results showed that both techniques led to implant integration and intimate contact between bone and the 2 implant surfaces. A significant increase in bone-to-implant contact and bone area fraction occupancy was observed as time elapsed at 2 and 4 weeks and for the calcium phosphate-coated implant surface compared with the alumina-blasted/acid-etched surface. Because the surgical drilling technique did not affect the early integration of plateau root form implants, the hypothesis was refuted.

• Evaluation of a nanometer roughness scale resorbable media-processed surface: a study in dogs.

  Authors: Charles Marin, Rodrigo Granato, Estevam A Bonfante, Marcelo Suzuki, Malvin N Janal, Paulo G Coelho

  Clinical oral implants research. 04/2011; 23(1):119-24.

  This study compared the biomechanical fixation and bone-to-implant contact (BIC) of implants with different surfaces treatment (experimental - resorbable blasting media-processed nanometer roughnessThis study compared the biomechanical fixation and bone-to-implant contact (BIC) of implants with different surfaces treatment (experimental - resorbable blasting media-processed nanometer roughness scale surface, and control - dual acid-etched) in a dog model. Surface characterization was made in six implants by means of scanning electron microscopic imaging, atomic force microscopy to evaluate roughness parameters, and X-ray photoelectron spectroscopy (XPS) for chemical assessment. The animal model comprised the bilateral placement of control (n=24) and experimental surface (n=24) implants along the proximal tibiae of six mongrel dogs, which remained in place for 2 or 4 weeks. Half of the specimens were biomechanically tested (torque), and the other half was subjected to histomorphologic/morphometric evaluation. BIC and resistance to failure measures were each evaluated as a function of time and surface treatment in a mixed model ANOVA. Surface texturing was significantly higher for the experimental compared with the control surface. The survey XPS spectra detected O, C, Al, and Ti at the control group, and Ca (∼0.2- 0.9%) and P (∼1.7- 4.1%) besides O, C, Al, and Ti at experimental surfaces. While no statistical difference in BIC was found between experimental and control surfaces or between 2 and 4 weeks in vivo, both longer time and use of experimental surface significantly increased resistance to failure. The experimental surface resulted in enhanced biomechanical fixation but comparable BIC relative to control, suggesting higher bone mechanical properties around the experimental implants.

• All-ceramic systems: laboratory and clinical performance.

  Authors: Petra C Guess, Stefan Schultheis, Estevam A Bonfante, Paulo G Coelho, Jonathan L Ferencz, Nelson R F A Silva

  Dental clinics of North America. 04/2011; 55(2):333-52, ix.

  Several all-ceramic systems have been developed in dentistry to meet the increased expectations of patients and dentists for highly aesthetic, biocompatible, and long-lasting restorations. However,Several all-ceramic systems have been developed in dentistry to meet the increased expectations of patients and dentists for highly aesthetic, biocompatible, and long-lasting restorations. However, early bulk fractures or chippings have led the research community to investigate the mechanical performance of the all-ceramic systems. This overview explores the current knowledge of monolithic and bilayer dental all-ceramic systems, addressing composition and processing mechanisms, laboratory and clinical performance, and possible future trends for all-ceramic materials.

• The effect of alterations on resorbable blasting media processed implant surfaces on early bone healing: a study in rabbits.

  Authors: Charles Marin, Estevam A Bonfante, Rodrigo Granato, Marcelo Suzuki, Jose M Granjeiro, Paulo G Coelho

  Implant dentistry. 04/2011; 20(2):167-77.

  Etching resorbable blasting media (RM) processed implants is a common engineering procedure, but the interplay between the resulting physicochemical properties and its effects on early bone healingEtching resorbable blasting media (RM) processed implants is a common engineering procedure, but the interplay between the resulting physicochemical properties and its effects on early bone healing have not been thoroughly addressed. Screw-root form implant surfaces were treated with 1 of 3 methods: grit (alumina) blasted/acid etching, RM, and RM + acid etching (RMAA). Surface topography (n = 3 each) was characterized by scanning electron microscopy and atomic force microscopy and chemical characterization by x-ray photoelectron spectroscopy analysis. The implants were placed at the distal femur of 16 rabbits, where 3 implants, 1 from each surface, were placed bilaterally remaining 4 and 8 weeks in vivo. After euthanization, one half of the specimens were torqued to interface failure at a rate of ∼0.196 radians/min and the other half were nondecalcified processed for histomorphology and bone-to-implant contact evaluation. Physicochemical characterization showed that the grit (alumina) blasted/acid-etched surface was rougher than RM and RMAA. Higher levels of calcium and phosphorous were observed for the RM surface compared with the RMAA surface. No significant differences were observed in torque and bone-to-implant contact between surfaces at 4 or 8 weeks. Histomorphologic evaluation showed woven bone formation around all surfaces at 4 weeks, and its initial replacement by lamellar bone at 8 weeks. Despite differences in texture/chemistry, all implant surfaces were biocompatible and osseoconductive, and led to comparable in vivo bone fixation and measurable histomorphometric parameters.

• Cements and adhesives for all-ceramic restorations.

  Authors: Adriana P Manso, Nelson R F A Silva, Estevam A Bonfante, Thiago A Pegoraro, Renata A Dias, Ricardo M Carvalho

  Dental clinics of North America. 04/2011; 55(2):311-32, ix.

  Dental cements are designed to retain restorations, prefabricated or cast posts and cores, and appliances in a stable, and long-lasting position in the oral environment. Resin-based cements wereDental cements are designed to retain restorations, prefabricated or cast posts and cores, and appliances in a stable, and long-lasting position in the oral environment. Resin-based cements were developed to overcome drawbacks of nonresinous materials, including low strength, high solubility, and opacity. Successful cementation of esthetic restorations depends on appropriate treatment to the tooth substrate and intaglio surface of the restoration, which in turn, depends on the ceramic characteristics. A reliable resin cementation procedure can only be achieved if the operator is aware of the mechanisms involved to perform the cementation and material properties. This article addresses current knowledge of resin cementation concepts, exploring the bonding mechanisms that influence long-term clinical success of all-ceramic systems.

• Biomechanical and histologic evaluation of non-washed resorbable blasting media and alumina-blasted/acid-etched surfaces.

  Authors: Paulo G Coelho, Charles Marin, Rodrigo Granato, Gabriela Giro, Marcelo Suzuki, Estevam A Bonfante

  Clinical oral implants research. 03/2011; 23(1):132-5.

  To compare the biomechanical fixation and histomorphometric parameters between two implant surfaces: non-washed resorbable blasting media (NWRBM) and alumina-blasted/acid-etched (AB/AE), in a dogTo compare the biomechanical fixation and histomorphometric parameters between two implant surfaces: non-washed resorbable blasting media (NWRBM) and alumina-blasted/acid-etched (AB/AE), in a dog model. The surface topography was assessed by scanning electron microscopy, optical interferometry and chemistry by X-ray photoelectron spectroscopy (XPS). Six beagle dogs of ∼1.5 years of age were utilized and each animal received one implant of each surface per limb (distal radii sites). After a healing period of 3 weeks, the animals were euthanized and half of the implants were biomechanically tested (removal torque) and the other half was referred to nondecalcified histology processing. Histomorphometric analysis considered bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Following data normality check with the Kolmogorov-Smirnov test, statistical analysis was performed by paired t-tests at 95% level of significance. Surface roughness parameters S(a) (average surface roughness) and S(q) (mean root square of the surface) were significantly lower for the NWRBM compared with AB/AE. The XPS spectra revealed the presence of Ca and P in the NWRBM. While no significant differences were observed for both BIC and BAFO parameters (P>0.35 and P>0.11, respectively), a significantly higher level of torque was observed for the NWRBM group (P=0.01). Bone morphology was similar between groups, which presented newly formed woven bone in proximity with the implant surfaces. A significant increase in early biomechanical fixation was observed for implants presenting the NWRBM surface.

• Effect of Si addition on Ca- and P-impregnated implant surfaces with nanometer-scale roughness: an experimental study in dogs.

  Authors: Paulo G Coelho, Rodrigo Granato, Charles Marin, Ryo Jimbo, Siyan Lin, Lukasz Witek, Marcelo Suzuki, Estevam A Bonfante

  Clinical oral implants research. 03/2011; 23(3):373-378.

  Objectives: To investigate the effect of Si addition on a nanometer-scale roughness Ca and P implant surfaces in a canine tibia model by biomechanical and histomorphometric evaluations. Material andObjectives: To investigate the effect of Si addition on a nanometer-scale roughness Ca and P implant surfaces in a canine tibia model by biomechanical and histomorphometric evaluations. Material and methods: The implant surfaces comprised a resorbable media CaP microblasted (control) and a CaP resorbable media+silica-boost microblasted (experimental) surfaces. Surfaces were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and optical interferometry (IFM) down to the nanometric level. The animal model involved the bilateral placement of control (n=24) and experimental surface (n=24) implants along the proximal tibiae of six dogs, remaining in vivo for 2 or 4 weeks. After euthanization, half of the specimens were torqued-to-interface failure, and the other half was subjected to histomorphologic and bone-to-implant contact (BIC) evaluation. Torque and BIC statistical evaluation was performed by the Friedman test at 95% level of significance, and comparisons between groups was performed by the Dunn test. Results: IFM and SEM observations depicted comparable roughness parameters for both implant surfaces on the micrometer and nanometer scales. XPS analysis revealed similar chemical composition, except for the addition of Si on the experimental group. Torque-to-interface failure and BIC mean values showed no significant differences (P=0.25 and 0.51, respectively) at both 2- and 4-week evaluation points for experimental and control groups. Early bone healing histomorphologic events were similar between groups. Conclusions: The experimental surface resulted in not significantly different biomechanical fixation and BIC relative to control. Both surfaces were biocompatible and osseoconductive. To cite this article: Coelho PG, Granato R, Marin C, Jimbo R, Lin S, Witek L, Suzuki M, Bonfante EA. Effect of Si addition on Ca- and P-impregnated implant surfaces with nanometer-scale roughness: an experimental study in dogs. Clin. Oral Impl. Res. 23, 2012; 373-378. doi: 10.1111/j.1600-0501.2010.02150.x.

• The effect of implant design on insertion torque and immediate micromotion.

  Authors: Amilcar C Freitas, Estevam A Bonfante, Gabriela Giro, Malvin N Janal, Paulo G Coelho

  Clinical oral implants research. 03/2011; 23(1):113-8.

  To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs. Thirty-six implants with identical thread design, but different cutting groove designTo evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs. Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (90° cut at the apex, tap design); and (3) Blossom(™) (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 90° by a digital torque gauge. Controlled lateral loads of 10 N followed by increments of 5 up to 100 N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction. While insertion torque increased as a function of number of turns for each design, the slope and final values increased (P<0.001) progressively from the Blossom to the fluted to the non-fluted design (M ± standard deviation [SD]=64.1 ± 26.8, 139.4 ± 17.2, and 205.23 ± 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (P<0.001) progressively from the Blossom to the fluted to the non-fluted design (M ± SD=530 ± 57.7, 585.9 ± 82.4, and 782.33 ± 269.4 μm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossom, fluted and non-fluted design groups, respectively. Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.

• Sealing Capability and SEM Observation of the Implant-Abutment Interface.

  Authors: Fabio C Lorenzoni, Paulo G Coelho, Gerson Bonfante, Ricardo M Carvalho, Nelson R F A Silva, Marcelo Suzuki, Thelma Lopes Silva, Estevam A Bonfante

  International journal of dentistry. 01/2011; 2011:864183.

  To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite,To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 μL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 μL water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P < .05) and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

• Characterization of five different implant surfaces and their effect on osseointegration: a study in dogs.

  Authors: Paulo G Coelho, Estevam A Bonfante, Roberto S Pessoa, Charles Marin, Rodrigo Granato, Gabriela Giro, Lukasz Witek, Marcelo Suzuki

  Journal of periodontology. 11/2010; 82(5):742-50.

  Chemical modification of implant surface is typically associated with surface topographic alterations that may affect early osseointegration. This study investigates the effects of controlled surfaceChemical modification of implant surface is typically associated with surface topographic alterations that may affect early osseointegration. This study investigates the effects of controlled surface alterations in early osseointegration in an animal model. Five implant surfaces were evaluated: 1) alumina-blasting, 2) biologic blasting, 3) plasma, 4) microblasted resorbable blasting media (microblasted RBM), and 5) alumina-blasting/acid-etched (AB/AE). Surface topography was characterized by scanning electron microscopy and optical interferometry, and chemical assessment by x-ray photoelectron spectroscopy. The implants were placed in the radius of six dogs, remaining 2 and 4 weeks in vivo. After euthanization, specimens were torqued-to-interface failure and non-decalcified-processed for histomorphologic bone-implant contact, and bone area fraction-occupied evaluation. Statistical evaluation was performed by one-way analysis of variance (P <0.05) and post hoc testing by the Tukey test. The alumina-blasting surface presented the highest average surface roughness and mean root square of the surface values, the biologic blasting the lowest, and AB/AE an intermediate value. The remaining surfaces presented intermediate values between the biologic blasting and AB/AE. The x-ray photoelectron spectroscopy spectra revealed calcium and phosphorus for the biologic blasting and microblasted RBM surfaces, and the highest oxygen levels for the plasma, microblasted RBM, and AB/AE surfaces. Significantly higher torque was observed at 2 weeks for the microblasted RBM surface (P <0.04), but no differences existed between surfaces at 4 weeks (P >0.74). No significant differences in bone-implant contact and bone area fraction-occupied values were observed at 2 and 4 weeks. The five surfaces were osteoconductive and resulted in high degrees of osseointegration and biomechanical fixation.

• Biomechanical and histomorphometric analysis of etched and non-etched resorbable blasting media processed implant surfaces: an experimental study in dogs.

  Authors: Charles Marin, Rodrigo Granato, Marcelo Suzuki, Malvin N Janal, Jose N Gil, Carlos Nemcovsky, Estevam A Bonfante, Paulo G Coelho

  Journal of the mechanical behavior of biomedical materials. 07/2010; 3(5):382-91.

  This study characterized the interplay between topography/chemistry and early bone response of etched and no-etched resorbable blasted media (RBM) processed surfaces. Screw-root form Ti-6Al-4VThis study characterized the interplay between topography/chemistry and early bone response of etched and no-etched resorbable blasted media (RBM) processed surfaces. Screw-root form Ti-6Al-4V implants treated with alumina blasting/acid-etching (AB/AE), RBM alone (RBM), and RBM + acid-etching (RBMa) were evaluated. The surface was characterized by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Implants placed in the tibia of dogs remained 3 and 5 weeks in vivo. Following euthanasia, half of the specimens were torqued to interface failure and the remaining subjected to bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) between threads evaluation. The AB/AE surface was rougher than the RBM and RBMa. Higher levels of calcium and phosphorous were observed for the RBM surface compared to the RBMa. No significant differences were observed in torque, BIC, and BAFO between surfaces. Woven bone formation at 3 weeks and its initial replacement by lamellar bone at 5 weeks were observed around all implants' surfaces.