Bone Remodeling Around Implants with External Hexagon and Morse-Taper Connections: A Randomized, Controlled, Split-Mouth, Clinical Trial.

OBJECTIVES: To evaluate clinical, radiographic, microbiologic, and biomechanical parameters related to bone remodeling around implants with external hexagon (EH) and Morse-taper (MT) connections. MATERIALS AND METHODS: Twelve totally edentulous patients received four custom-made implants in the interforaminal region of the mandible. Two of those implants had the same macroscopic design, but different prosthetic connections. All patients received an immediate implant-supported prosthesis. Clinical parameters (periimplant probing pocket depth (PPD), modified gingival index (mGI), and mucosal thickness (MTh)) were evaluated at 12 months follow-up. The distance between the top of the implant and the first bone-to-implant contact (IT-FBIC) was evaluated on standardized digital peri-apical radiographs acquired at 1, 3, 6, and 12 months follow-up. Samples of the subgingival microbiota were collected 1, 3, and 6 months after implant loading and used for the quantification of Tanerella forsythia, Porphyromonas gingivalis, Aggragatibacter actinomycetemcomitans, Prevotella intermedia, and Fusobacterium nucleatum. Further, 36 computerized-tomography based finite element (FE) models were accomplished, simulating each patient under three loading conditions. RESULTS: The evaluated clinical parameters were equal for EH and MT implants. Mean IT-FBIC was significantly different between the tested connections (1.17 ± 0.44 mm for EH, and 0.17 ± 0.54 mm for MT, considering all evaluated time periods). No significant microbiological differences could be observed between tested connections. FE analysis showed a significantly higher peak of equivalent (EQV) strain (p = 0.005) for EH (mean 3,438.65 µÎµ) compared to MT (mean 840.98 µÎµ) connection. CONCLUSIONS: Radiographic periimplant bone loss depends on the implant connection type. MT connections showed less periimplant bone loss, compared to EH connections.

Influence of Connection Types and Implant Number on the Biomechanical Behavior of Mandibular Full-Arch Rehabilitation.

PURPOSE: To evaluate the influence of different implant numbers and connection types on the biomechanical behavior of mandibular full-arch implant-supported rehabilitation. MATERIALS AND METHODS: Computed tomography-based finite element models comprising a totally edentulous mandible and 3.8 × 13-mmdiameter implants, abutments, abutment screws, bar retaining screw, and bar were constructed. Different implant numbers (three, four, and five implants) and loading conditions (symmetrical/balanced, unilateral, and posterior with diverse loading magnitudes) were simulated for both external hex and Morse-taper connections. The peak equivalent strain (EQV strain) in the bone and the peak of von Mises stress (EQV stress) in the abutment screw and bar retaining screw were evaluated. RESULTS: Lower strain values were observed for a symmetrical loading distribution. Considering the same loading conditions, significantly higher bone strain levels were observed for external hex, compared with the Morse-taper connection. The number of implants had no significant influence on strain levels in bone, irrespective of the connection types. Compared with the external hex connection, the Morse-taper connection type presented significantly lower EQV stress values in abutment screws, but significantly higher stress in the bar retaining screw. Increasing the number of implants significantly reduced the EQV stress in the abutment screw and bar retaining screw. CONCLUSION: The Morse-taper connection type significantly decreased the strain levels in peri-implant bone, while increasing the stress in bar retaining screws. A smaller number of implants in an inferior full-arch rehabilitation slightly increased the stress in the abutment and bar retaining screws. Balanced adjustments of the loading improve the biomechanics of a mandibular full-arch rehabilitation.

Avaliação da estabilidade dos tecidos duros e moles em implantes imediatos com carga imediata em área estética: estudo clínico prospectivo longitudinal / Soft and hard tissue maintenance following placement of immediate-loaded implants in the aesthetic zone: a prospective longitudinal clinical trial

O objetivo desse trabalho foi avaliar, clínica e radiograficamente (bi/tridimensional), as alterações em tecidos moles e duros encontradas após a colocação de implantes imediatos com carga imediata em alvéolos pós-extração. Dez pacientes tratados com implantes imediatos com carga imediata nos incisivos central e lateral superiores foram incluídos. Parâmetros clínicos foram avaliados em fotografias padronizadas tiradas após a instalação do implante ( baseline ) e 1, 3 e 6 meses após. Parâmetros bi- e tridimensionais foram medidos em tomografias Cone-Beam, para avaliar a estabilidade do tecido ósseo na região vestibular. Também foram realizadas análises clínicas e fotográficas dos tecidos moles, para avaliar a sua estabilidade durante o período de avaliação. Não houve variações estatisticamente significativas nos parâmetros clínicos e radiográficos avaliados, tendo sido demonstrada uma manutenção de 94% do volume do osso vestibular. Implantes imediatos com carga imediata apresentam boa estabilidade dos tecidos moles e duros peri-implantares...

To evaluate by clinical and radiographic bi- and tridimensional means the soft and hard tissues alterations following immediate implant placement and loading in postextraction sockets in theanterior maxilla. Ten patients, treated with immediate-loaded implants in the maxillary central or lateral incisors, were evaluated in this study. Clinical parameters were evaluated in standardized pictures taken at baseline (immediately after), and 1, 3, and 6 months after provisional implant-supported single crown placement. Bi- and tridimensional radiographic parameters were evaluated from standardized digital periapical radiographies and from CBCT images. The volume of the buccal bone wall covering the central millimeter of the implant was also assessed in the CBCT images. The variation for all clinical, bi- and tridimensional parameters assessed was non-statistically significant. There was 94% maintenance of bone volume. The parameters assessed showed good clinical, bi- and tridimensional radiographic stability of soft and hard tissues for implants immediately placed and loaded in aesthetic zones...

Remodelação óssea de implantes com conexão hexágono externo e elementos de retenção no módulo da crista sob carregamento imediato – estudo clínico prospectivo longitudinal de um ano / Bone remodeling of implants with external hexagon connection and retention elements at the crestal module under immediate loading – a 1-year longitudinal prospective clinical trial

Objetivo: avaliar a remodelação óssea radiográfica ao redor de implantes hexágono externo (EH) que possuem roscas no módulo da crista. Material e métodos: doze pacientes desdentados totais receberam quatro implantes (Ø 3,8 mm x 13 mm) customizados na região interforaminal. Doze desses implantes foram hexágono externo com roscas no módulo da crista. Todos os pacientes receberam uma prótese implantossuportada imediata. A distância entre o topo do implante e o primeiro contato osso/implante (IT-FBIC) foi avaliada em radiografias periapicais digitais padronizadas adquiridas em um, três, seis e 12 meses de acompanhamento. A comparação entre vários períodos de observação foi realizada utilizando análise de variância (Anova) para medidas repetidas, seguida pelo teste post-hoc de Tukey. Resultados: a variação radiográfica da perda óssea peri-implantar foi significativamente diferente entre os períodos de acompanhamento (p < 0,001). A média de IT-FBIC foi de 1,17 ± 0,44 mm, depois de 12 meses de carregamento funcional. Conclusão: a remodelação óssea peri-implantar ocorrerá para implantes com hexágono externo, independentemente da presença de elementos de retenção no módulo da crista do implante

Objective: to evaluate the radiographic bone remodeling around implants using external hexagon (EH) with a threaded implant crestal module. Material and methods: twelve patients with totally edentulous mandibles received four custom-made (Ø 3.8 x 13 mm) implants in the interforaminal region. Twelve of the implants were external hexagon with a threaded implant crestal module. All patients received an immediate implant-supported prosthesis. The distance between the top of the implant and the first bone-to-implant contact (IT-FBIC) was evaluated on standardized digital periapical radiographs acquired at one, three, six, and 12 months of follow-up. Comparison among multiple observation periods was performed using repeated-measures analysis of variance (Anova), followed by a Tukey post-hoc test. Results: the radiographic periimplant bone loss was significantly different among the follow-up periods (p < 0.001). Mean IT-FBIC was 1.17 mm ± 0.44 mm, at 12 months follow-up period. Conclusions: radiographic periimplant bone remodeling will occur for implants using external hexagon, regardless of the presence of retention elements at the implant crestal module.

Biomechanical evaluation of platform switching: different mismatch sizes, connection types, and implant protocols.

BACKGROUND: It is not yet well understood to what extent different implant-abutment mismatch sizes and implant-abutment connection types may influence the peri-implant biomechanical environment of implants in different clinical situations. METHODS: Computed tomography-based finite element models comprising a maxillary central incisor socket and 4.5 × 13 mm outer-diameter implants with external and internal hex connection types were constructed. The abutments were designed with diameters of 3.5 mm (platform switching [PS] with 1 mm of diametral mismatch [PS - 1]), 4.0 mm (PS with 0.5 mm of diametral mismatch [PS - 0.5]), and 4.5 mm (conventional matching implant-abutment design [CD]). Analysis of variance at the 95% confidence interval was used to evaluate peak equivalent strain (EQV strain) in the bone, bone volume affected by a strain >4,000 µÎµ (EQV strain >4,000 µÎµ), the peak von Mises stress (EQV stress) in abutment screw, and the bone-implant relative displacement. RESULTS: Similar bone strain levels (EQV strain and EQV strain >4,000 µÎµ) were encountered in PS - 1, PS - 0.5, and CD models for immediately placed implants, independent of the connection type. For immediately loaded implants, slightly smaller peak EQV strain and EQV strain >4,000 µÎµ were found for PS - 1. However, for both connection types in osseointegrated models, the higher the mismatch size, the lesser the amount of strain found. CONCLUSIONS: The increase in mismatch size of PS configuration results in a significant decrease of strain levels in bone for osseointegrated implants, principally for external hex connections. No significant effect of PS could be noted in immediately placed implants.