RESUMO
INTRODUCTION: Bidirectional vertical ridge augmentation in the posterior maxilla is very challenging. PURPOSE: To evaluate the regenerative potential of micrografts, derived from periosteum or bone tissue, added to an anorganic xenograft in vertical reconstruction of the posterior maxilla, by a prospective, controlled study. MATERIALS AND METHODS: After clinical selection and the analysis of CBCT scans, 24 posterior maxillary sites, in 19 patients, were treated by using Barbell Technique®. Sites requiring both inlay and onlay reconstruction were enrolled in the study. In the Control Group (CG, n = 8), a xenograft was used in the inlay site and for the onlay site, a 1:1 mix of xenograft and an autograft was used. In Test Group 1 (TG1, n = 8), both inlay and onlay sites were grafted with the xenograft associated with the micrografts derived from periosteum. In Test Group 2 (TG2, n = 8), both inlay and onlay sites were grafted with the xenograft associated with the micrografts derived from bone. Six months after the procedures, CBCT scans were obtained, and bone biopsy samples were harvested during implant placement surgery. The bone specimens were analyzed histomorphometrically, by measuring the percentages of vital mineralized tissue (VMT), non vital mineralized tissue (NVMT) and non mineralized tissue (NMT). Immunohistochemically, the levels of VEGF were categorized by a score approach. RESULTS: Histomorphometric analysis revealed, for the inlay grafts, no significant difference among the groups for VMT, NVMT and NMT. However, for onlay grafts, CG achieved a higher amount of VMT in comparison with TG2, and the opposite occurred for NMT values. In this regard, no statistical difference was observed between CG and TG1. Concerning immunohistochemistry, the VEGF values for CG and TG1 were slightly higher than those obtained by TG2 for both inlay and onlay grafts, but without statistical significance. CBCT analysis showed a similar level of gain for all groups, for both inlay and onlay bone augmentation sites. Clinically, one implant (in CG) within a total of 50 implants installed, had early failure and was replaced after 3 months. All patients received implant supported prosthesis. CONCLUSION: This study indicated that the clinical use of micrograft derived from periosteum may have some potential to increase bone formation in onlay reconstructions, unlike the micrograft derived from bone tissue.
RESUMO
Este estudo teve por objetivo avaliar a estabilidade de implantes de carga imediata ou precoce, em diferentes intervalos de tempo. Material e Métodos: foram extraídos os pré-molares mandibulares, bilateralmente, de oito cães e, após 12 semanas, cada cão recebeu seis implantes (três em cada lado da mandíbula). A carga foi aplicada em pares, em um implante de cada lado, sendo que o primeiro par recebeu carga imediata, o segundo par após sete dias, e o terceiro par após 14 dias. Em cada período, as medidas de estabilidade dos implantes foram realizadas por frequência de ressonância (ISQ). Após 12 semanas, uma nova leitura da estabilidade dos implantes foi realizada. A análise estatística foi feita usando modelo linear de efeitos mistos, que é uma generalização do modelo linear padrão (Anova). Diferenças foram consideradas significantes quando p < 0,05. Resultados: a estabilidade do implante mudou no decorrer do tempo para todos os protocolos de carga, apresentando aumento significativo na estabilidade final, mas as variações foram semelhantes para os três grupos estudados. Nos períodos de sete dias e 14 semanas, o protocolo de carga imediata apresentou menor estabilidade de implante do que os protocolos de sete e 14 dias. Conclusão: a estabilidade do implante diminui nos períodos iniciais após a cirurgia e aumenta no período de 14 semanas. A estabilidade dos implantes do protocolo de carga imediata é menor do que a dos protocolos de sete e 14 dias, sugerindo cautela para seu uso...
This study aimed to evaluate implant stability in function with immediate or early loading protocols at different time intervals. Material and Methods: The mandibular premolars of eight dogs were pulled bilaterally. After 12 weeks, each dog received 6 implants (3 at each mandibular side). Implant loading was performed for each implant pair according to the following periods: immediate (fi rst pair), 7 days later (second pair), 14 days later (third pair). Implant stability measurements were performed by means of resonance frequency for each period. After 12 weeks, new readings of implant stability were obtained. The statistical analysis was performed using a mixed linear model, which is a generalization of the standard linear model (Anova), with differences considered signifi cant at p<0.05. Results: Implant stability changed throughout time for all loading protocols, presenting a significant increase in fi nal stability values, but variations were similar for the three studied groups. At 7- and 14-week periods, immediate loading protocol presented lower implant stability than 7-day or 14-day protocols. Conclusions: Implant stability diminishes in the initial periods after surgery, and increases in a 14-week period. In the middle-term, there were no statistically significant differences in the stability of immediately-loaded implants, one or two weeks after implant placement...
Assuntos
Animais , Cães , Implantação Dentária , Prótese Parcial ImediataRESUMO
PURPOSE: The aim of this study was to evaluate, through histomorphometric analysis, the effect that different loading times would have on the bone response around implants. MATERIALS AND METHODS: Three Replace Select implants were placed on each side of the mandible in eight dogs (n = 48 implants). One pair of implants was selected for an immediate loading protocol (IL). After 7 days, the second pair of implants received prostheses for an early loading protocol (EL). Fourteen days after implant placement, the third pair of implants received prostheses for advanced early loading (AEL). Following 12 weeks of prosthetics, counted following the positioning of the metallic crowns for the AEL group, the animals were sacrificed and the specimens were prepared for histomorphometric analysis. The differences between loading time in the following parameters were evaluated through analysis of variance: bone-to-implant contact, bone density, and crestal bone loss. RESULTS: The mean percentage of bone-to-implant contact for IL was 77.9% +/- 1.71%, for EL it was 79.25% +/- 2.11%, and for AEL it was 79.42% +/- 1.49%. The mean percentage of bone density for IL was 69.97% +/- 3.81%, for EL it was 69.23% +/- 5.68%, and for AEL it was 69.19% +/- 2.90%. Mean crestal bone loss was 1.57 +/- 0.22 mm for IL, 1.23 +/- 0.19 mm for EL, and 1.17 +/- 0.32 mm for AEL. There was no statistical difference for any of the parameters evaluated (P > .05). CONCLUSION: Different early loading times did not seem to significantly affect the bone response around dental implants.