Ridge Architecture Preservation Following Minimally Traumatic Exodontia Techniques and Guided Tissue Regeneration.

OBJECTIVE: To compare hard-tissue healing after 3 exodontia approaches. MATERIALS AND METHODS: Premolars of dogs were extracted: (1) flapless, (2) flap, and (3) flap + socket coverage with polytetrafluoroethylene (dPTFE) nonresorbable membrane (flap + dPTFE). Animals were euthanized at 1 and 4 weeks. Amount of bone formation within socket and socket total area were measured. RESULTS: Amount of bone formation revealed significant difference between 1 and 4 weeks; however, there was no differences among groups. Socket total area decreased after 4 weeks, and the flap + dPTFE group showed significantly higher socket total area. As a function of time and group, flap + dPTFE 4 weeks presented similar socket total area values relative to flap + dPTFE at 1 week, and significantly higher socket total area than flapless and flap. The histological sections revealed almost no bone formation within socket after 1 week, which increased for all groups at 4 weeks. CONCLUSION: Socket coverage with polytetrafluoroethylene (dPTFE) membrane showed to effectively preserve bone architecture. Bone formation within sockets was not influenced by tooth extraction technique.

The Effect of CAD/CAM Crown Material and Cement Type on Retention to Implant Abutments.

PURPOSE: To evaluate the pullout resistance of CAD/CAM implant-supported crowns cemented with provisional and definitive cements on Ti-base implant abutments. MATERIALS AND METHODS: Sixty crowns were milled for use in Ti-base implant abutments and divided (n = 15/group) according to material, as follows: (a) [Pr] Temporary acrylic resin; (b) [Co-Cr] Cobalt-Chromium alloy; (c) [Zr] polycrystalline zirconia; and (d) [Ti] titanium. The cementation was performed with RelyX Temp NE (RxT) cement or RelyX U200 self-etching resin cement, under a 50 N (5 kg) load for 10 minutes. Twenty-four hours after cementation, the crowns were subjected to the pullout test in a universal test machine, at a 1.0 mm/min crosshead speed. The tests were performed first without cement to evaluate frictional resistance (Baseline), then with provisional cement (RelyX Temp NE without cement again (Baseline After RxT), and finally with resin cement (U200). The results were analyzed by ANOVA and Tukey test (p < 0.05). RESULTS: Data evaluation as a function of cement type demonstrated the superiority of resin-based cements relative to provisional and baseline groups (p < 0.01). While Co-Cr crowns presented the highest pullout strength values, Pr showed the lowest values (data collapsed over cement) (p < 0.001). Retentiveness data as a function of both factors demonstrated similar pullout resistance between groups without cement (p < 0.001), except Zr baseline. Also, Co-Cr presented higher pullout strength compared to other materials. CONCLUSIONS: Self-adhesive resin cement exhibited superior retention compared to temporary cement, regardless of crown material. Co-Cr and titanium presented higher levels of retention to Ti-base abutment after being cemented.

Bulk Fill Composites: An Anatomic Sculpting Technique.

UNLABELLED: Composite resins have been routinely used for posterior cavities due to a phasedown on amalgam as a restorative option. However, clinical problems related to polymerization shrinkage demands careful and specific techniques for placement of the composite layers. New low shrinkage composites are now marketed for bulk filling of cavities without the need of a traditional layering. With this new concept, the restoration can be built in one or two layers, depending on the classification of the bulk fill material. This article discusses and presents two alternative techniques using the low shrinkage composites, suggesting a called "amalgam-like sculpting technique," one using a flowable bulk fill and other a regular bulk fill material. Clinical cases illustrate these two alternatives compared with the layered technique. CLINICAL SIGNIFICANCE: New techniques using low shrinkage composites for bulk filling can provide a simpler technical approach for the clinician in sculpting and generating highly esthetic posterior composites.

Drilling dimension effects in early stages of osseointegration and implant stability in a canine model.

BACKGROUND: This study histologically evaluated two implant designs: a classic thread design versus another specifically designed for healing chamber formation placed with two drilling protocols. STUDY DESIGN: Forty dental implants (4.1 mm diameter) with two different macrogeometries were inserted in the tibia of 10 Beagle dogs, and maximum insertion torque was recorded. Drilling techniques were: until 3.75 mm (regular-group); and until 4.0 mm diameter (overdrilling-group) for both implant designs. At 2 and 4 weeks, samples were retrieved and processed for histomorphometric analysis. For torque and BIC (bone-to-implant contact) and BAFO (bone area fraction occupied), a general-linear model was employed including instrumentation technique and time in vivo as independent. RESULTS: The insertion torque recorded for each implant design and drilling group significantly decreased as a function of increasing drilling diameter for both implant designs (p<0.001). No significant differences were detected between implant designs for each drilling technique (p>0.18). A significant increase in BIC was observed from 2 to 4 weeks for both implants placed with the overdrilling technique (p<0.03) only, but not for those placed in the 3.75 mm drilling sites (p>0.32). CONCLUSIONS: Despite the differences between implant designs and drilling technique an intramembranous-like healing mode with newly formed woven bone prevailed.

Retention strength of cobalt-chromium vs nickel-chromium titanium vs CP titanium in a cast framework association of removable partial overdenture.

AIM: There is little information considering the framework association between cast clasps and attachments. The aim of this study was to evaluate the retention strength of frameworks match circumferential clasps and extra resilient attachment cast in three different alloys (cobalt-chromium, nickel-chromium titanium and commercially pure titanium), using two undercut (0.25 and 0.75 mm) and considering different period of time (0, 1/2, 1, 2, 3, 4 and 5 years). METHODS: Using two metallic matrices, representing a partially edentulous mandibular right hemiarch with the first molar crown, canine root and without premolars, 60 frameworks were fabricated. Three groups (n = 20) of each metal were cast and each group was divided into two subgroups (n = 10), corresponding the molar undercut of 0.25 mm and 0.75 mm. The nylon male was positioned at the matrix and attached to the acrylic resin of the prosthetic base. The samples were subjected to an insertion and removal test under artificial saliva environment. RESULTS: The data were analyzed and compared with ANOVAs and Tukey's test at 95% of probability. The groups cast in cobaltchromium and nickel-chromium-titanium had the highest mean retention strength (5.58 N and 6.36 N respectively) without significant difference between them, but statistically different from the group cast in commercially pure titanium, which had the lowest mean retention strength in all the periods (3.46 N). The association frameworks using nickel-chromium- titanium and cobalt-chromium could be used with 0.25 mm and 0.75 mm of undercut, but the titanium samples seems to decrease the retention strength, mainly in the 0.75 mm undercut. The circumferential clasps cast in commercially pure titanium used in 0.75 mm undercuts have a potential risk of fractures, especially after the 2nd year of use. CONCLUSION: This in vitro study showed that the framework association between cast clasp and an extra resilient attachment are suitable to the three metals evaluated, but strongly suggest extra care with commercially pure titanium in undercut of 0.75 mm. CLINICAL SIGNIFICANCE: Frameworks fabricated in Cp Ti tend to decrease in retentive strength over time and have a potential risk of fracture in less than 0.75 mm of undercut.

Synergistic Effects of Implant Macrogeometry and Surface Physicochemical Modifications on Osseointegration: An In Vivo Experimental Study in Sheep.

This study evaluates the influence of two surface physicochemical modifications on osseointegration parameters of a healing chamber implant design. We examine dental implants with internal and external trapezoidal threads that have the following surface modifications: dual acid etching (DAE) and nano-hydroxyapatite (HA) coating over DAE surface (Nano). We installed implants in the right ilium of sheep and conducted histologic/metric analyses after 3 and 12 wk in vivo. We quantified the percentage of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO) within implant threads. Histologic micrographs indicate early bone formation within the healing chambers of implants with Nano surface relative to DAE surface. Histomorphometric analysis demonstrates there to be no significant differences in %BIC between 3 and 12 wk (p = 0.298). Compared to DAE, Nano shows more bone formation in contact with implant, regardless of time (p < 0.025). We observe > %BAFO at 12 wk relative to 3 wk, which differs significantly for Nano (p < 0.038). Implant surface treatment affects the amounts of bone formation within healing chambers, with Nano significantly outperforming DAE at 12 wk (p < 0.025). Nano presents a synergistic effect with implant design, improving osseointegration parameters.

Practice-Based Clinical Evaluation of Dental Implants Placed with Immediate or Delayed Loading Protocols: One-Year Follow-Up.

We evaluate bone remodeling and prostheses survival of immediately provisionalized with occlusal loading and delayed loading (DL) single implants placed in the posterior region after 1-yr follow-up in dental practices. Included in the study are patients selected to receive one regular implant (4 × 10 mm) for single tooth replacement in healed ridge sockets in the mandible and maxilla. Implants are immediately loaded or delayed functionally loaded with metal ceramic crowns, depending on peak insertion torque value. All implants are clinically and radiographically evaluated at T1, immediately postoperatively; T2, 60 d; T3, 180 d; and T4, 360 d. Measurements between implant platform and top of alveolar bone crest at distal and mesial areas are performed using periapical radiographs. Data are statistically evaluated through two-way repeated measures of analysis of variance following post hoc comparisons using the Tukey test (p < 0.05). Ten specialists working in ten different practices treat 36 patients who receive one implant each with internal conical connection (hybrid implant system, 4 × 10 mm) (Emfils; Itu, Brazil). Results show that bone-level alterations in immediate (IM; 0.56 mm; confidence interval [CI]: ± 0.21 mm) and delayed (0.65 mm; CI: ± 0.19 mm) groups are not significantly different (p = 0.515) during the course of the 1-yr observation period. In both groups, statistically significant progressive bone-level remodeling occurs through the evaluated follow-up time points (p < 0.047). All prostheses are rated "alpha," presenting 100% success at 1-yr follow-up. The loading method does not influence bone-remodeling levels around IM or DL at the posterior region after 1-yr follow-up. No prostheses complications are reported.

Mechanical testing and finite element analysis of orthodontic teardrop loop.

INTRODUCTION: Understanding how teeth move in response to mechanical loads is an important aspect of orthodontic treatment. Treatment planning should include consideration of the appliances that will meet the desired loading of the teeth to result in optimized treatment outcomes. The purpose of this study was to evaluate the use of computer simulation to predict the force and the torsion obtained after the activation of tear drop loops of 3 heights. METHODS: Seventy-five retraction loops were divided into 3 groups according to height (6, 7, and 8 mm). The loops were subjected to tensile load through displacements of 0.5, 1.0, 1.5, and 2.0 mm, and the resulting forces and torques were recorded. The loops were designed in AutoCAD software(2005; Autodesk Systems, Alpharetta, GA), and finite element analysis was performed with Ansys software(version 7.0; Swanson Analysis System, Canonsburg, PA). Statistical analysis of the mechanical experiment results was obtained by ANOVA and the Tukey post-hoc test (P < .01). The correlation test and the paired t test (P < .05) were used to compare the computer simulation with the mechanical experiment. RESULTS AND CONCLUSIONS: The computer simulation accurately predicted the experimentally determined mechanical behavior of tear drop loops of different heights and should be considered an alternative for designing orthodontic appliances before treatment.

Clinical Comparison of At-Home and In-Office Dental Bleaching Procedures: A Randomized Trial of a Split-Mouth Design.

The objective of this split-mouth clinical study was to compare a combination of in-office and at-home dental bleaching with at-home bleaching alone. Two applications of in-office bleaching were performed, with one appointment per week, using 38% hydrogen peroxide. At-home bleaching was performed with or without in-office bleaching using 10% carbamide peroxide in a custom-made tray every night for 2 weeks. The factor studied was the bleaching technique on two levels: Technique 1 (in-office bleaching combined with home bleaching) and Technique 2 (home bleaching only). The response variables were color change, dental sensitivity, morphology, and surface roughness. The maxillary right and left hemiarches of the participants were submitted to in-office placebo treatment and in-office bleaching, respectively (Phase 1), and at-home bleaching (Phase 2) treatment was performed on both hemiarches, characterizing a split-mouth design. Enamel surface changes and roughness were analyzed with scanning electron microscopy and optical interferometry using epoxy replicas. No statistically significant differences were observed between the bleaching techniques for either the visual or the digital analyses. There was a significant difference in dental sensitivity when both dental bleaching techniques were used, with in-office bleaching producing the highest levels of dental sensitivity after the baseline. Microscopic analysis of the morphology and roughness of the enamel surface showed no significant changes between the bleaching techniques. The two techniques produced similar results in color change, and the combination technique produced the highest levels of sensitivity. Neither technique promoted changes in morphology or surface roughness of enamel.

Positive Biomechanical Effects of Titanium Oxide for Sandblasting Implant Surface as an Alternative to Aluminium Oxide.

The aim of this study was to evaluate the physico-chemical properties and the in vivo host response of a surface sandblasted with particles of titanium oxide (TiO2) followed by acid etching as an alternative to aluminium oxide. Thirty titanium disks manufactured in the same conditions as the implants and 24 conventional cylindrical implants were used. Half of the implants had a machined surface (Gcon) while in the other half; the surface was treated with particles of TiO2 followed by acid etching (Gexp). Surface characterization was assessed by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), profilometry, and wettability. For the in vivo test, 12 implants of each group were implanted in the tibia of 6 rabbits, and were reverse torque tested after periods of 30 or 60 days after implantation. Following torque, SEM was utilized to assess residual bone-implant contact. The surface characterization by SEM showed a very homogeneous surface with uniform irregularities for Gexp and a small amount of residues of the blasting procedure, while Gcon presented a surface with minimal irregularities from the machining tools. Wettability test showed decreased contact angle for the Gcon relative to the Gexp. The Gexp removal torque at 30 and 60 days was 28.7%, and 33.2% higher relative to the Gcon, respectively. Blasting the surface with particles of TiO2 represents an adequate option for the surface treatment of dental implants, with minimal risk of contamination by the residual debris from the blasting procedure.

Influence of implant shape, surface morphology, surgical technique and bone quality on the primary stability of dental implants.

The primary stability of dental implants has been investigated before, but a study of the influence of implant shape, size and surface morphology (machined, acid etched or anodized), surgical technique (press-fit or undersized) and substrate (natural or simulated bone) on the primary stability of dental implants has not been reported. The present work intends to fill this gap. In this work, six different dental implants were inserted into and removed from synthetic and natural bone while measuring the torque. A total of 255 dental implants with three shapes, four sizes and three surface topographies were inserted into pig rib, PTFE and polyurethane. The implant sites were prepared using straight and tapered drills. The primary stability was estimated from the maximum insertion torque. Comparisons between samples were based on the maximum insertion torque (MIT), the maximum removal torque (MRT) and the torque ratio (TR=MRT/MIT). The insertion torque into pig ribs showed larger dispersion. All parameters (shape, size and surface morphology of the implant, surgical technique and substrate type) were found to have a significant influence on primary stability. The insertion of a tapered implant requires a higher torque than the insertion of a straight implant. Surface treatments improve the primary stability. The influence of the surgical technique is smaller than that of implant size and shape. The highest insertion torque was that of anodized tapered implants inserted into undersized sites. Finally, the primary stability of dental implants is highly dependent on implant design, surgical technique and substrate type.

Evaluation of collagen-based membranes for guided bone regeneration, by three-dimensional computerized microtomography.

OBJECTIVE: The aim of this study was to evaluate the use of a collagen-based membrane compared with no treatment on guided bone regeneration by 3-dimensional computerized microtomography (µCT). STUDY DESIGN: Defects were created between the mesial and distal premolar roots of the second and third premolars (beagle dogs; n = 8). A collagen-based membrane (Vitala; Osteogenics Biomedical Inc., TX, USA) was placed in one of the defects (membrane group; n = 16), and the other was left untreated (no-membrane group; n = 16). Left and right sides provided healing samples for 2 and 16 weeks. Three-dimensional bone architecture was acquired by µCT and categorized as fully regenerated (F, bone height and width) or nonregenerated (N). RESULTS: Chi-square tests (95% level of significance) showed that tooth did not have an effect on outcome (P = .5). Significantly higher F outcomes were observed at 16 weeks than 2 weeks (P = .008) and in membrane group than in no-membrane group (P = .008). CONCLUSIONS: The collagen-based membrane influenced bone regeneration at the furcation.

Reliability and failure modes of implant-supported Y-TZP and MCR three-unit bridges.

PURPOSE: Chipping within veneering porcelain has resulted in high clinical failure rates for implant-supported zirconia (yttria-tetragonal zirconia polycrystals [Y-TZP]) bridges. This study evaluated the reliability and failure modes of mouth-motion step-stress fatigued implant-supported Y-TZP versus palladium-silver alloy (PdAg) three-unit bridges. MATERIALS AND METHODS: Implant-abutment replicas were embedded in polymethylmethacrylate resin. Y-TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact-tested to obtain ultimate failure load. In each framework group, 18 specimens were distributed across three step-stress profiles and mouth-motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. RESULTS: PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y-TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (two-sided at 90% confidence intervals) for a "mission" of 50,000 and 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft, Tucson, AZ, USA). No difference in reliability was observed between groups for a mission of 50,000. Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y-TZP. CONCLUSIONS: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300 N. Failure modes differed between materials.

Micro-morphological changes prior to adhesive bonding: high-alumina and glassy-matrix ceramics.

The aim of this study was to qualitatively demonstrate surface micro-morphological changes after the employment of different surface conditioning methods on high-alumina and glassy-matrix dental ceramics. Three disc-shaped high-alumina specimens (In-Ceram Alumina, INC) and 4 glassy-matrix ceramic specimens (Vitadur Alpha, V) (diameter: 5 mm and height: 5 mm) were manufactured. INC specimens were submitted to 3 different surface conditioning methods: INC1--Polishing with silicon carbide papers (SiC); INC2--Chairside air-borne particle abrasion (50 microm Al2O3); INC3 - Chairside silica coating (CoJet; 30 microm SiOx). Vitadur Alpha (V) specimens were subjected to 4 different surface conditioning methods: V1--Polishing with SiC papers; V2 - HF acid etching; V3--Chairside air-borne particle abrasion (50 microm Al2O3); V4--Chairside silica coating (30 microm SiOx). Following completion of the surface conditioning methods, the specimens were analyzed using SEM. After polishing with SiC, the surfaces of V specimens remained relatively smooth while those of INC exhibited topographic irregularities. Chairside air-abrasion with either aluminum oxide or silica particles produced retentive patterns on both INC and V specimens, with smoother patterns observed after silica coating. V specimens etched with HF presented a highly porous surface. Chairside tribochemical silica coating resulted in smoother surfaces with particles embedded on the surface even after air-blasting. Surface conditioning using air-borne particle abrasion with either 50 microm alumina or 30 microm silica particles exhibited qualitatively comparable rough surfaces for both INC and V. HF acid gel created the most micro-retentive surface for the glassy-matrix ceramic tested.

Influência da modificação do desenho de infraestruturas cerâmicas e metálicas na vida útil à fadiga e no modo de falha / Influence of modified framework design in all-ceramic and metal-ceramic crowns fatigue life and failure mode

Avaliar a influência da modificação do desenho da infraestrutura na vida útil à fadiga e no modo de falha em coroas metalo-cerâmicas e alumina infiltrada por vidro. Quarenta réplicas de um primeiro molar superior foram produzidas para receber coroas com infraestrutura padrão ou modificada. A infraestrutura modificada consistiu do desenho padrão (0,5 mm de espessura) aumentada por uma cinta lingual, unindo dois postes proximais. A carga (30-300 N) foi aplicada por um endentador metálico (3,18 mm raio) na superfície oclusal, durante 106 ciclos ou até a falha. A cada 125.000 ciclos o teste era interrompido para avaliar os danos. Fraturas catastróficas ou da porcelana de revestimento e a presença da trinca cone interno estendendo-se a infraestrutura foram os critérios utilizados para definir falha. As superfícies fraturadas e as polidas foram analisadas com estereomicroscópio e por microscopia eletrônica de varredura. A distribuição de Weibull foi utilizada para a análise estatística. A vida útil à fadiga da metalo-cerâmica foi significativamente maior que da alumina; contudo, a modificação não alterou este parâmetro nos grupos metálico ou cerâmico. Os grupos metalo-cerâmico apresentaram trincas cone interno sem fraturas da porcelana de revestimento. O grupo alumina com infraestrutura padrão apresentou principalmente fratura da porcelana de revestimento, enquanto que no grupo alumina com infraestrutura modificada se observou cone interno. A vida útil à fadiga não melhorou com a modificação no desenho das infraestruturas. O modo de falha variou de acordo com o material da infraestrutura.

To evaluate the effect of framework design on the fatigue life and failure modes of metal-ceramic and glass-infiltrated alumina. Forty composite resin tooth-replica of a prepared maxillary first molar were produced to receive crowns of a standard or modified framework design. Core design modification consisted of a standard, connecting to proximal struts. R-ratio fatigue loading was delivered with a spherical steel indenter (3.18 mm radius) on the center of the occlusal surface at a 30-300 N load range, until completion of 106 cycles or failure. Fatigue was interrupted every 125.000 cycles for damage evaluation. Catastrophic fracture, chipping within veneering porcelain, or inner cone crack reaching the core-veneer interface were the criteria for failure. Fractured and polished surfaces were characterized under light polarized microscopy followed by scanning electron microscopy. Weibull distribution fit was used for examining differences between groups. The highest fatigue life was observed for metal-ceramic crowns, but no significant differences were observed for groups with or without framework design modification. Failure modes of metal-ceramic comprised inner cone cracks without porcelain fracture. Glass-infiltrated alumina standard crowns presented bulk fracture whereas glass-infiltrated alumina modified crowns failed mainly through veneer. Fatigue life was not improved with framework design modification. Failure modes varied according to core material.

Micro-morphological changes prior to adhesive bonding: high-alumina and glassy-matrix ceramics

The aim of this study was to qualitatively demonstrate surface micro-morphological changes after the employment of different surface conditioning methods on high-alumina and glassy-matrix dental ceramics. Three disc-shaped high-alumina specimens (In-Ceram Alumina, INC) and 4 glassy-matrix ceramic specimens (Vitadur Alpha, V) (diameter: 5 mm and height: 5 mm) were manufactured. INC specimens were submitted to 3 different surface conditioning methods: INC1 - Polishing with silicon carbide papers (SiC); INC2 - Chairside air-borne particle abrasion (50 µm Al2O3); INC3 - Chairside silica coating (CoJet; 30 µm SiOx). Vitadur Alpha (V) specimens were subjected to 4 different surface conditioning methods: V1 - Polishing with SiC papers; V2 - HF acid etching; V3 - Chairside air-borne particle abrasion (50 µm Al2O3); V4 - Chairside silica coating (30 µm SiOx). Following completion of the surface conditioning methods, the specimens were analyzed using SEM. After polishing with SiC, the surfaces of V specimens remained relatively smooth while those of INC exhibited topographic irregularities. Chairside air-abrasion with either aluminum oxide or silica particles produced retentive patterns on both INC and V specimens, with smoother patterns observed after silica coating. V specimens etched with HF presented a highly porous surface. Chairside tribochemical silica coating resulted in smoother surfaces with particles embedded on the surface even after air-blasting. Surface conditioning using air-borne particle abrasion with either 50 µm alumina or 30 µm silica particles exhibited qualitatively comparable rough surfaces for both INC and V. HF acid gel created the most micro-retentive surface for the glassy-matrix ceramic tested.

Conceitos Básicos de Pesquisa in vivo aplicada à Implantodontia / Basic concepts of in vivo implant research

As altas taxas de sucesso das reabilitações orais sobreimplantes osseointegráveis metálicos consolidaram esta modalidade de tratamento. Porém, é incessante a busca pela otimização da resposta implante/hospedeiro imediata e a longo prazo, sendo hoje o principal fator motivador das investigações nesta área. O impacto das alterações produzidas nos implantes nas diferentes escalas macro, micro e nanométricas com o objetivo de acelerar a resposta do hospedeiro, permitindo a reabilitação em tempos menores do que aqueles inicialmente propostos nos primórdios da Implantodontia moderna, serão discutidos. Devido à quase infinidade de superfícies disponíveis no mercado, uma classificação objetiva será apresentada para facilitar a comunicação entre profissionais, pesquisadores e indústria. O efeito destas modificações, das técnicas cirúrgicas e as implicações clínicas na osseointegração serão abordados com suporte em estudos in vivo.

High success rates of implant dentistry have made it a consolidated treatment modality. However, the quest for implant/host improved response has been the main driving force in research involving the topic. The impact of macro-, micro, and nanometric alterations tailored to foster early implant/host response allowing final rehabilitation at earlier time frames will be discussed. Considering the virtually “infinite” amount of implant surfaces available in the market, a novel classification code will be presented in attempt to facilitate communication between dental professionals, researchers and industry personal. The impact of implant surface modifications and surgical technique on clinical aspects of osseointegration will be discussed based on in vivo sudies

Avaliação biomecânica e histológica de implantes com diferentes macrogeometrias no período inicial de osseointegração: estudo experimental em cães / Early biomechanical and histological analyses of different implant macrogeometries: an experimental study in beagle dogs

Desde que o conceito de osseointegração foi introduzido na Odontologia, várias mudanças ocorreram no modelo e na texturização de superfície dos implantes dentários. O objetivo deste estudo foi avaliar biomecânica e histologicamente diferentes macrogeometrias no período inicial da osseointegração na porção proximal da tíbia de cães Beagle. Seis cães Beagle adultos foram utilizados, onde 24 implantes tratados com jateamento com micropartículas e ataque ácido foram inseridos na porção proximal da tíbia bilateralmente (dois implantes por tíbia), 12 implantes cilíndricos com roscas triangulares (grupo controle) e 12 implantes cônicos com roscas trapezoidais (grupo experimental). Após a eutanásia, as tíbias foram removidas e destinadas ao teste de torque de remoção e processamento histológico. A análise estatística foi realizada através de teste t com intervalo de confiança de 95%. Os resultados para o torque de remoção foram 70 ± 20 Ncm e 120 ± 20 Ncm (média ± 95% de intervalo de confiança). Diferença estatisticamente significante entre os grupos foi encontrada (p < 0,001). Histologicamente, ambos os grupos apresentaram adequada biocompatibilidade e osseocondução com neoformação óssea nas regiões cortical e medular da tíbia. Baseado nos resultados obtidos, a macrogeometria com o tratamento de superfície empregados promoveu a osseointegração nos períodos iniciais do reparo e a macrogeometria do grupo experimental melhorou o desempenho para o torque de remoção comparado ao grupo controle. Novos estudos são necessários para confirmar suas potenciais vantagens.

Since the concept of osseointegration was introduced in dentistry, several changes concerning surface texture and macrodesign of dental implants were implemented. The objective of this study was to evaluate the effect of different implant macrogeometries on the early biomechanical and histomorphologic response in a beagle dog proximal tibia model. Six adult beagle dogs were used, and the implants with a grit-blasted and acid-etched surface were bilaterally placed along the proximal tibia (2 per limb)- 12 conic shaped with trapezoidal threads (experimental) and 12 cylindrical implants with triangular threads (control). After animal sacrifice, the limbs were retrieved and mechanical test and histological processing were performed. Statistical evaluation was performed by a Student´s t-test at 95% level of confidence. Removal torque test mean values were 70 ± 20Ncm and 120 ± 20Ncm for control and experimental groups, respectively (p < 0.001). Histological observations showed that both implant groups were biocompatible and osseoconductive, presenting newly formed bone at regions of cortical and trabecular bone. Based on results obtained, both macrogeometries and surface treatment presented osseointegration at early implantation times, and the experimental group geometry improved torque to interface fracture relative to the control geometry. Additional studies are necessary to confirm its potential benefits.

Avaliação biomecânica de um tratamento de superfície à base de biocerâmica absorvível: estudo em cães / Biochemical evaluation of an absorbable bioceramic based surface treatment: a study in dogs

O objetivo deste estudo foi avaliar a fixação biomecânica de superfície de implante tratada com biocerâmica absorvível e ataque ácido (NanossTM - experimento) comparando com uma superfície tratada por duplo ataque ácido (controle) em cães. Métodos: o modelo animal compreendeu a instalação de 24 implantes na porção proximal da tíbia de 6 cães (12 por superfície, 2 por membro), que permaneceram por 2 e 4 semanas de experimentação in vivo. Após a eutanásia os espécimes foram destinados ao teste biomecânico (torque para fratura interfacial). ANOVA com 95% de intervalo de confiança e o teste Tukey para comparações múltiplas foram utilizados. Foi encontrada diferença significativa nos valores do teste biomecânico entre os grupos NanossTM (p < 0,03) e controle. Conclusão: de acordo com o teste biomecânico, os períodos iniciais da osseointegração foram afetados positivamente pela superfície NanossTM, quando comparados ao grupo controle.

The objective of this study was to analyses the biomechanical fixation of a bioceramic grit-blasted and acid-etched surface (NanossTM, test), versus a dual acid-etched implant surface (control) in a dog model. Methods: the animal model comprised the placement of 24 implants along the proximal tibiae of 6 dogs (12 per surface, 2 per limb), which remained for 2 and 4 weeks implantation time. After euthanization specimens were biomechanically tested (torque to facial fracture). ANOVA at 95% level of confidence and Tukey post-hoc test was utilized for multiple comparisons. Results: Significantly higher removal torque was observed for the NanossTM group compared to control one (p < 0.03). Conclusion: according to the biomechanical results, early biomechanical fixation was positively affected by the NanossTM surface compared to the dual-acid etched surface.

Próteses fixas implanto-suportadas de 3 elementos: zircônia versus metalocerâmica / Three-unit implant-supported fixed parcial dentures: zirconia versus metal-ceramic

A falha coesiva na porcelana de revestimento de próteses com infraestruturas de policristais de zircônia tetragonal estabilizada por ítrio (PZT-I) tem causado elevadas taxas clínicas de fracassos. No presente estudo avaliou-se a confiabilidade e modos de fratura de próteses fixas implanto-suportadas confeccionadas em uma liga de paládio-prata (PdAg) e em PZT-I, submetidas à fadiga acelerada progressiva. Embebeu-se análogos de implantes em uma resina acrílica. Infraestruturas em PZT-I e PdAg (n = 21/grupo) foram fabricadas, revestidas com porcelana, cimentadas e submetidas a uma carga estática (n = 3/grupo) para obtenção dos valores de resistência à fratura. Em seguida, 18 espécimes de cada grupo foram distribuídos ao longo de 3 perfis de estresse progressivo e submetidos à fadiga em água com a carga aplicada na cúspide vestibular do pôntico. Encontrou-se no grupo PdAg um modo de fratura incluindo trincas flexurais na área do conector competindo com a falha coesiva da porcelana, enquanto que as próteses em PZT-I apresentaram falha coesiva na porcelana de revestimento. O cálculo da confiabilidade (Alta Pro, Relia Soft, intervalo de confiança de 90%, bilateral) revelou confiabilidade significativamente inferior para o grupo PZT-I na finalização de uma missão de 100.000 ciclos a 300 N quando comparada ao grupo PdAg. Concluiu-se que para uma missão de 100.000 ciclos a 300 N a confiabilidade é mais alta para a prótese metalocerâmica quando comparada à em PZT-I. Os modos de fratura diferiram entre os grupos.

Statement of problem: chipping within veneering porcelain has resulted in high clinical failure rates for implant-supported zirconia (Y-TZP) bridges. This study evaluated the reliability and failure modes of mouth-motion step-stress fatigued implant-supported Y-TZP versus Palladium-Silver alloy (PdAg) three-unit bridges. Methods: Implant-abutment replicas wereembedded in polymethylmethacrylate resin. Y-TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact tested to obtain ultimate failure load. In each framework group eighteen specimens were distributed across 3 stepstress profiles and mouth-motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. Results: PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y-TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (2-sided at 90% confidence intervals) for a “mission” of 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft). Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y-TZP. Conclusion: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300N. Failure modes differed between materials.