Microbiologic Analysis of Immediately Loaded Full-Arch Implant-Retained Prosthesis Protocol After 2 Years of Loading: A Retrospective Study.

PURPOSE: The All-on-4 treatment concept has been shown to be an effective clinical procedure; however, to date, no studies have analyzed the subgingival microbiota present in these restorations. The purpose of this study was to evaluate the microbial profile of the subgingival biofilm around dental implants placed in the All-on-4 protocol and compare the microbial profile around axial and tilted implants. MATERIALS AND METHODS: Fourteen subjects treated by the All-on-4 concept were evaluated clinically and microbiologically. Subgingival biofilm was collected from each patient, and the amount of 40 species of bacteria was assessed using the checkerboard DNA-DNA hybridization technique. RESULTS: The results for the indices of probing depth (PD), bleeding on probing, marginal bleeding, and visible plaque were 2.32 mm, 46%, 60%, and 57%, respectively. Tilted implants presented a significantly higher mean PD and Plaque Index compared with axial implants (P < .05). Fusobacterium nucleatum ssp vincentii, Veillonella parvula, and Fusobacterium nucleatum ssp polymorphum were found in higher levels; however, no difference in the microbial composition was observed between tilted and axial implants (P > .05). Tilted implants presented statistically higher mean levels for the orange complex in relation to the axial implants (P < .05). CONCLUSION: Despite the clinical success rate of the All-on-4 protocol, the subgingival biofilm of tilted implants presented a higher proportion for the orange complex pathogens in comparison to axial implants. These data could suggest that subjects with this modality of implant-supported restoration must be aware that they need a more rigorous maintenance protocol.

Three-year clinical prospective follow-up of extrasinus zygomatic implants for the rehabilitation of the atrophic maxilla.

BACKGROUND: Placement of extrasinus zygomatic implants to support implant-supported rehabilitation is still controversial due to the scarcity of data. PURPOSE: To evaluate the clinical outcomes of 94 extrasinus zygomatic implants, installed laterally to the maxillary sinus, for rehabilitation of the edentulous atrophic maxillae. MATERIALS AND METHODS: A total of 42 patients (mean age 58 years) with severely atrophic maxillae were treated between November 2010 and July 2011, and followed up until July 2014. A total of 273 implants (94 zygomatic implants and 179 conventional implants) were used. The patients were followed in a standardized clinical and radiographic method. RESULTS: During the 3-year study period, 1 zygomatic implant and 4 conventional implants failed, resulting in a survival rate of 98.9% and 97.7% respectively. All restorations with titanium-welded bars were installed either 3 days after surgery (immediate loading) or 6 months after surgery (delayed loading), and were successful until the last follow-up appointment, except for minor technical problems. No patient presented any type of sinus adverse event. No other significant occurrences were reported. CONCLUSION: This 3-year clinical follow-up study indicates that extrasinus zygomatic implants represent predictable treatment option atrophic maxillae. Further longitudinal prospective clinical studies are necessary to confirm these results.

Tratamento de maxilas atróficas por meio de fixações zigomáticas sob carregamento imediato: relatos de coorte histórico com 8-60 meses de acompanhamento / Treatment of atrophic maxillary arches with zygomatic fixations under immediate loading: historical cohort report with 8-60 months of follow-up

Objetivo: este estudo retrospectivo avaliou o índice de sucesso de restaurações implantossuportadas de função imediata, com fixações zigomáticas associadas aos implantes convencionais. Material e métodos: foram avaliadas as fichas clínicas de todos os pacientes atendidos na clínica particular dos autores. Os critérios de inclusão foram: edentulismo total ou parcial de maxila, com indicação de extração dos dentes remanescentes; saúde geral compatível; ausência de hábitos parafuncionais; capacidade física para a manutenção e higienização das próteses; seios maxilares saudáveis; ausência de enxertia óssea prévia; procedimentos cirúrgicos e protéticos pelo mesmo cirurgião e protesista. Após exame prévio e confecção do guia cirúrgico, os pacientes foram operados com a técnica preconizada por Stella e Warner, 2000. Os controles foram realizados após dez, 30, 60 dias e, posteriormente, a cada seis meses para avaliação dos implantes, da higiene oral, da condição da prótese e da oclusão. Resultados: 12 pacientes com maxilas atróficas foram incluídos no estudo, sendo oito mulheres (66,7%) e quatro homens (33,3%). A idade dos pacientes variou entre 41 e 73 anos, com média de 56,5. Foram instalados 22 implantes zigomáticos e 38 implantes convencionais.As próteses foram instaladas e ajustadas de 24 a 36 horas após o procedimento cirúrgico. Ao longo das avaliações, os pacientes apresentaram ausência de infecção peri-implantar e poucas complicações compatíveis com o procedimento realizado (três cirúrgicas, seis protéticas). Conclusão: nos limites desse estudo observacional, longitudinal e retrospectivo com implantes zigomáticos, pôde-se concluir que todos os implantes avaliados estavam nos critérios de sobrevivência e de sucesso no período de observação.

Objective: this retrospective study evaluated the success index of immediate implant-supported restorations with zygomatic fi xations associated to conventional implants. Material and methods: the clinical records of all treated patients at the author´s clinics were evaluated. The inclusion criteria were as follows: partial or total maxillary edentulism, indications for tooth extraction, adequate general health, lack of parafunctional habits, capacity for good oral hygiene, healthy maxillary sinuses, lack of previous bone grafting, surgical and prosthetic procedures made by the same practitioner. After previous examining and surgical guide fabrication, all surgeries were performed according the Stella and Warner´s technique (2000). Follow-ups were made at 10, 30, 60 days, and each six months for implant, occlusal, and oral hygiene related conditions. Results: 12 patients with atrophic maxillae were included, being 8 women (66.7%) and 4 men (33.3%). Patient´s age varied from 41 to 73 years-old (mean 56,5 years). Twenty-two zygomatic and 38 conventional implants were, installed. All prostheses were delivered at 24 or 36 hours after the surgical procedure. No peri-implant infections were observed, and a few complications (3 surgical, 6 prosthodontic) were seen. Conclusion: within the limits of this observational, longitudinal, and retrospective study with zygomatic implants, all installed fixtures fit the survival criteria over the studied period.

Mechanical comparison of experimental conical-head abutment screws with conventional flat-head abutment screws for external-hex and internal tri-channel implant connections: an in vitro evaluation of loosening torque.

PURPOSE: This study compared the loosening torque of experimental conical-head abutment screws to that of conventional flat-head screws of implants with external-hex (EH) and internal tri-channel (IT) connections before and after mechanical loading. MATERIALS AND METHODS: Forty-four implant/screw/abutment assemblies were divided into four groups: EH/flat-head screw (EH), IT/flat-head screw (IT), EH/conical-head screw (EHCS), and IT/conical-head screw (ITCS). Three assemblies from each group were analyzed in a stereoscopic magnifier and then returned to their respective groups. One assembly was removed from each group and transversely sectioned for optical microscopy analysis. Abutments were tightened at 32 Ncm of torque; after 10 minutes, loosening torque was measured. The same abutments were then retightened with 32 Ncm of torque; after 10 minutes, they were mechanically loaded for 300,000 cycles and loosening torque was again measured. Data were collected and an exploratory analysis was performed. Comparisons were made by orthogonal contrasts using a linear mixed effects model (random and fixed effects). RESULTS: Comparisons before mechanical cycling showed significant differences between groups except for EH vs IT and EHCS vs ITCS. After mechanical cycling, only the comparisons EH vs IT and EHCS vs ITCS showed no significant differences. Considering the same group, before and after mechanical cycling, all comparisons showed significant differences. CONCLUSIONS: The shape of the abutment screw head significantly influenced loosening torque: conical-head screws showed higher loosening torque values than conventional flat-head screws before and after loading. The implant/abutment connection design exerted no significant influence on loosening torque.

Restoration of the edentulous maxilla using extrasinus zygomatic implants combined with anterior conventional implants: a retrospective study.

PURPOSE: To report on the clinical outcome of 150 extrasinus zygomatic implants placed lateral to the maxillary sinus and combined with conventional implants in the anterior maxilla for the implant-supported rehabilitation of the edentulous maxilla. MATERIALS AND METHODS: All patients included in this study presented with completely or partially edentulous maxillae with any remaining teeth indicated for extraction. Indications for extractions in partially edentulous patients included longitudinal fractures, periodontal disease, endodontic failure, perforated roots, and prosthetic convenience. All patients showed severe resorption of the posterior maxilla. Each patient was treated with at least four implants, with a minimum of one zygomatic implant. No bone grafting was performed. The zygomatic implants were placed outside the sinus, lateral to the maxillary sinus. The patients were followed with standardized clinical and radiographic examinations. RESULTS: Seventy-five patients with severely atrophic maxillae (mean age, 52 years) were treated between 2003 and 2006. In all, 436 implants (150 zygomatic implants and 286 conventional implants) were placed. Two conventional implants failed during the study period, and two zygomatic implants were removed. All the prostheses were successful. No patients presented sinusitis. No loosened or fractured screws on any implants were recorded. CONCLUSION: Extrasinus zygomatic implants, when combined with conventional implants in the anterior maxilla, represent a predictable treatment option for the atrophic edentulous maxilla. Further studies are necessary to evaluate the long-term prognosis of these implants.

Immediate loading of implants placed in fresh extraction sockets in the molar area with flapless and graftless procedures: a case series.

The purpose of this study was to present a protocol for the replacement of single teeth lost in the molar area with immediate implantation in fresh extraction sockets, no flap reflections or grafting procedures, and immediate loading. Twenty-three implants were placed in 20 patients between 2000 and 2006. No implants were lost and no signs of significant bone resorption, loss of osseointegration, or soft tissue complications were reported. The results of this study indicate that this protocol may be a feasible alternative for the replacement of condemned molars.

Abrasion wear resistance of different artificial teeth opposed to metal and composite antagonists.

UNLABELLED: One of the most important properties of artificial teeth is the abrasion wear resistance, which is determinant in the maintenance of the rehabilitation's occlusal pattern. OBJECTIVES: This in vitro study aims to evaluate the abrasion wear resistance of 7 brands of artificial teeth opposed to two types of antagonists. MATERIAL AND METHODS: Seven groups were prepared with 12 specimens each (BIOLUX & BL, TRILUX & TR, BLUE DENT & BD, BIOCLER & BC, POSTARIS & PO, ORTHOSIT & OR, GNATHOSTAR & GN), opposed to metallic (M & nickel-chromium alloy), and to composite antagonists (C & Solidex indirect composite). A mechanical loading device was used (240 cycles/min, 4 Hz speed, 10 mm antagonist course). Initial and final contours of each specimen were registered with aid of a profile projector (20x magnification). The linear difference between the two profiles was measured and the registered values were subjected to ANOVA and Tukey's test. RESULTS: Regarding the antagonists, only OR (M = 10.45 +/- 1.42 microm and C = 2.77 +/- 0.69 microm) and BC (M = 6.70 +/- 1.37 microm and C = 4.48 +/- 0.80 microm) presented statistically significant differences (p < 0.05). Best results were obtained with PO (C = 2.33 +/- 0.91 microm and M = 1.78 +/- 0.42 microm), followed by BL (C = 3.70 +/- 1.32 microm and M = 3.70 +/- 0.61 microm), statistically similar for both antagonists (p>0.05). Greater result variance was obtained with OR, which presented the worse results opposed to Ni-Cr (10.45 +/- 1.42 microm), and results similar to the best ones against composite (2.77 +/- 0.69 microm). CONCLUSIONS: Within the limitations of this study, it may be concluded that the antagonist material is a factor of major importance to be considered in the choice of the artificial teeth to be used in the prosthesis.

Abrasion wear resistance of different artificial teeth opposed to metal and composite antagonists

One of the most important properties of artificial teeth is the abrasion wear resistance, which is determinant in the maintenance of the rehabilitation's occlusal pattern. OBJECTIVES: This in vitro study aims to evaluate the abrasion wear resistance of 7 brands of artificial teeth opposed to two types of antagonists. MATERIAL AND METHODS: Seven groups were prepared with 12 specimens each (BIOLUX & BL, TRILUX & TR, BLUE DENT & BD, BIOCLER & BC, POSTARIS & PO, ORTHOSIT & OR, GNATHOSTAR & GN), opposed to metallic (M & nickel-chromium alloy), and to composite antagonists (C & Solidex indirect composite). A mechanical loading device was used (240 cycles/min, 4 Hz speed, 10 mm antagonist course). Initial and final contours of each specimen were registered with aid of a profile projector (20x magnification). The linear difference between the two profiles was measured and the registered values were subjected to ANOVA and Tukey's test. RESULTS: Regarding the antagonists, only OR (M = 10.45 ± 1.42 µm and C = 2.77 ± 0.69 µm) and BC (M = 6.70 ± 1.37 µm and C = 4.48 ± 0.80 µm) presented statistically significant differences (p < 0.05). Best results were obtained with PO (C = 2.33 ± 0.91 µm and M = 1.78 ± 0.42 µm), followed by BL (C = 3.70 ± 1.32 µm and M = 3.70 ± 0.61 µm), statistically similar for both antagonists (p>0.05). Greater result variance was obtained with OR, which presented the worse results opposed to Ni-Cr (10.45 ± 1.42 µm), and results similar to the best ones against composite (2.77 ± 0.69 µm). CONCLUSIONS: Within the limitations of this study, it may be concluded that the antagonist material is a factor of major importance to be considered in the choice of the artificial teeth to be used in the prosthesis.

Fracture resistance of the implant-abutment connection in implants with internal hex and internal conical connections under oblique compressive loading: an in vitro study.

The objective of this study was to verify if differences in the design of internal hex (IH) and internal conical (IC) connection implant systems influence fracture resistance under oblique compressive forces. Twenty implant-abutment assemblies were utilized: 10 with IH connections and 10 with IC connections. Maximum deformation force for IC implants (90.58 +/- 6.72 kgf) was statistically higher than that for IH implants (83.73 +/- 4.94 kgf) (P = .0182). Fracture force for the IH implants was 79.86 +/- 4.77 kgf. None of the IC implants fractured. The friction-locking mechanics and the solid design of the IC abutments provided greater resistance to deformation and fracture under oblique compressive loading when compared to the IH abutments.

Effect of repeated torque/mechanical loading cycles on two different abutment types in implants with internal tapered connections: an in vitro study.

OBJECTIVES: Internal tapered connections were developed to improve biomechanical properties and to reduce mechanical problems found in other implant connection systems. The purpose of this study was to evaluate the effects of mechanical loading and repeated insertion/removal cycles on the torque loss of abutments with internal tapered connections. MATERIAL AND METHODS: Sixty-eight conical implants and 68 abutments of two types were used. They were divided into four groups: groups 1 and 3 received solid abutments, and groups 2 and 4 received two-piece abutments. In groups 1 and 2, abutments were simply installed and uninstalled; torque-in and torque-out values were measured. In groups 3 and 4, abutments were installed, mechanically loaded and uninstalled; torque-in and torque-out values were measured. Under mechanical loading, two-piece abutments were frictionally locked into the implant; thus, data of group 4 were catalogued under two subgroups (4a: torque-out value necessary to loosen the fixation screw; 4b: torque-out value necessary to remove the abutment from the implant). Ten insertion/removal cycles were performed for every implant/abutment assembly. Data were analyzed with a mixed linear model (P< or =0.05). RESULTS: Torque loss was higher in groups 4a and 2 (over 30% loss), followed by group 1 (10.5% loss), group 3 (5.4% loss) and group 4b (39% torque gain). All the results were significantly different. As the number of insertion/removal cycles increased, removal torques tended to be lower. It was concluded that mechanical loading increased removal torque of loaded abutments in comparison with unloaded abutments, and removal torque values tended to decrease as the number of insertion/removal cycles increased.

Estudo comparativo da dissipação de tensões em fixações zigomáticas instaladas internamente ou externamente ao seio maxilar: uma análise 3D pelo método de elementos finitos / Comparative study on the stress dissipation of zygomatic fixtures installed internal or external to the maxillary sinus: a 3D finite element method analysis

As fixações zigomáticas são utilizadas em reabilitações de maxilas edêntulas severamente atróficas, proporcionando ancoragem no osso zigomático. Modificações na técnica original de instalação destas fixações possibilitam um melhor posicionamento de sua emergência, favorecendo a reabilitação protética. Atualmente, são utilizadas técnicas de instalação internas ou externas ao seio maxilar. O comportamento biomecânico das fixações zigomáticas sob carregamento mecânico ainda é um tema obscuro, devido à inexistência de modelos confiáveis e elucidativos. Este estudo analisou, através do método de elementos finitos, a dissipação de tensões em fixações zigomáticas instaladas internamente ou externamente ao seio maxilar. Os resultados mostraram uma distribuição de tensões mais homogênea nas fixações zigomáticas instaladas externamente ao seio maxilar. Concluiu-se que a técnica exteriorizada proporcionou maior área de contato osso/fixação, que a posição palatinizada da emergência das fixações na técnica original gerou uma maior angulação da fixação e maior braço de alavanca na prótese, e que para ambas as técnicas foram observadas menores tensões no osso zigomático em relação à maxila.

The zygomatic fixtures are a valuable alternative to the maxillary reconstructions with bone grafts in the rehabilitation of severely atrophic edentulous maxillae. Modifications to the original installation technique of these fixations allowed a better positioning their emergence, favoring the prosthetic rehabilitation. Nowadays techniques internal and external to the maxillary sinus are used. The biomechanical behavior of the zygomatic fixtures under mechanichal loading remain obscure, due to the inexistence of reliable and elucidative models. This study analyzed with the finite element method the stress dissipation on zygomatic fixtures installed internally or externally to the maxillary sinus. The results showed a better stress distribution on the zygomatic fixtures installed externally to the maxillary sinus. It was concluded that the exteriorized technique provided a greater area of bone/implant contact, that the palatal emergence of the fixation on the original technique generated a higher angulation of the fixation and a greater lever arm on the prosthesis, and that low tensions are observed in the zygomatic bone in both techniques.

RM Bridge: uma nova abordagem protético reabilitadora para o tratamento dos desdentados totais / RM Bridge: a new rehabilitation prosthetic approach

A RM Bridge associada ao sistema All-on-4® é uma modalidade de tratamento para o desdentado que elimina a necessidade de enxertos e permite a função imediata do paciente. Este artigo apresenta o protocolo e as particularidades da RM Bridge empregada na reabilitação de desdentados totais.

Reabilitação da maxila atrófica sem enxertos ósseos: resultados de um novo protocolo utilizado em casos de edentulismo total / Rehabilitation of the atrophic maxillae without bone grafts: results of a new protocol utilized in cases of complete edentulism

A reabilitação dos desdentados totais com próteses fixas implanto-suportadas é uma alternativa de tratamento com altos índices de sucesso e mais de 40 anos de aplicação clínica. Os procedimentos de enxertia óssea necessários nas técnicas convencionais são de alta morbidade e indesejados pelos pacientes. Esse artigo avalia os resultados clínicos obtidos com um protocolo no qual a reabilitação dos pacientes edêntulos é realizada sem a realização de enxertos ósseos, mesmo em casos de atrofia severa da maxila, através da utilização de fixações zigomáticas e implantes convencionais.