Vula Papalexiou

Influence of Interimplant Distance on Papilla Formation and Bone Resorption: A Clinical-radiographic Study in Dogs

Implant esthetics has been the focus of attention for the past decade, and one vital issue is the effect of interimplant distance on interimplant papilla formation and crestal bone loss. The aim of this study was to evaluate the effect of 1, 2, and 3 mm of interimplant distance on papilla formation and crestal resorption in submerged and nonsubmerged Ankylos implants after prosthetic restoration. Bilateral mandibular premolars of 7 dogs were extracted, and after 12 weeks each dog received 8 implants. Implants were placed so that 3 interimplant distances were created at 1 mm (group 1), 2 mm (group 2), and 3 mm (group 3). The sides and the position of the groups were randomly selected. Twelve weeks after placement, the implants received metallic prostheses that allowed 5 mm of space between the prosthetic contact point (CP) and the crestal bone (CB). After 8 weeks, the distance between the CP and the papilla (CP-P) and the gingival height at the distal proximal aspect of the prosthesis (CP-DE) was clinically measured. Radiographic images were obtained to measure the distance of the CP to the CB within the interimplant surfaces (CP-IP) and adjacent to the edentulous surfaces (CP-ED). The clinical measurement of CP-P for submerged and nonsubmerged implants was 3.57+/-1.17 mm and 3.10+/-0.82 mm for group 1, 3.57+/-0.78 mm and 3.16+/- 0.87 mm for group 2, and 3.35+/- 0.55 mm and 3.07+/-0.93 mm for group 3. The CP-DE was 3.25+/-0.77 mm for submerged and 2.78+/- 0.64 mm for nonsubmerged implants. The CP-IP for the submerged and nonsubmerged implants was 6.91+/-0.95 mm and 7.68+/-2.73 mm for group 1, 7.46+/-1.43 mm and 5.87+/-1.71 mm for group 2, and 7.72+/-0.81 mm and 7.59+/-1.33 mm for group 3. The CP-ED was 6.77+/-1.33 mm for submerged implants and 6.03+/-1.58 mm for nonsubmerged implants. There were no statistical significant differences for any of the measured parameters. We conclude that when the distance from the CP to the CB was 5 mm, interimplant distances of 1 to 3 mm did not affect papilla formation or crestal resorption of submerged or nonsubmerged implants in the dog model.

Crestal Bone Loss Minimized When Following the Crestal Preparation Protocol: A Histomorphometric Study in Dogs

Initial breakdown of the implant-tissue interface generally begins at the crestal region in successfully osseointegrated implants. The purpose of this study was to evaluate the effect on crestal bone loss (CBL) around implants specially developed for immediate loading with a unique crestal drill. After 8 weeks postextraction, 6 young male mongrel dogs received 48 implants (XiVE) in the region corresponding to the 4 mandibular premolars. The implant sites were prepared according to the manufacturers protocol with conventional standard drills. Before implant placement, the crestal drill was used in the experimental group but not in the control group. After a healing period of 12 weeks, the dogs were sedated and euthanized. Through linear measurements, from the top of the implant to the first bone-implant contact, the amount of CBL was determined. The histomorphometric results of CBL (mean +/- SEM) were 0.88 +/- 0.13 mm (range 0.0-3.0 mm) in the experimental group and 1.69 +/- 0.17 mm (range 0.0-4.2 mm) in the control group. The difference was statistically significant (P < .05) when the implants were used as the experimental units. The statistical analysis also revealed significance when the dogs were used as the experimental units (P < .05). When the median was used for analyses, the CBL was 0.44 mm for the experimental group and 1.91 mm for the control group. Crestal bone loss was minimized when the crestal preparation protocol was carefully followed by using the osseocondensating XiVE implant system.

Efeito da deficiência de estrógeno no preenchimentode defeitos ósseos tratados ou não com biomaterial:um estudo radiográfico em ratas

Objetivos: O objetivo deste estudo foi avaliar radiograficamente o preenchimento osseo de defeitos criados em tibia de ratas ovariectomizadas e nao ovariectomizadas, preenchidos por coagulo ou material substituto osseo. Materiais e metodos: Foram utilizadas 30 ratas wistar, sendo que 15 foram ovariectomizadas(grupo OV) e 15 ratas nao receberam ovariectomia (grupo NOV). Decorridos 60 dias da cirurgia de ovariectomia,ambos os grupos foram submetidos a cirurgia para confeccao de defeitos osseos nas tibias. A tibia direita foi preenchida por coagulo, e a esquerda, por biomaterial sintetico (Bone Ceramic®), formando os seguintes grupos: grupos nao ovariectomizados com defeitos preenchidos por coagulo (grupo NOV/C) ou por biomaterial (grupo NOV/B), e grupos ovariectomizados com defeitos preenchidos por coagulo (grupoOV/C) ou por biomaterial (grupo OV/B). Decorridos 60 dias da cirurgia de confeccao dos defeitos e seus preenchimentos, as ratas foram mortas e suas tibias removidas. A densidade ossea das tibias foi avaliada em radiografias digitais e as imagens foram estudadas no programa de imagem ImageJ, por examinador unico.Para a analise estatistica, utilizou-se o teste Anova a dois criterios multifatoriais completos com α < 0,05.Resultados: A porcentagem media de preenchimento osseo para cada grupo foi: grupo NOV/C, 71,55%;grupo NOV/B, 70,44%; grupo OV/C, 21,03% e grupo OV/B, 58,93%. Conclusao: Com base nos resultados par obtidos,pode-se concluir que a deficiencia de estrogeno interferiu no grau de preenchimento osseo em defeitos cirurgicamente criados em tibias de ratas, com ou sem o uso de um biomaterial.