Effect of Different Doses of Synthetic Parathyroid Hormone (1-34) on Bone around Implants: a Preclinical Rat Model.

The aim of this study was to evaluate the effect of a lower dose of parathyroid hormone- PTH (1-34) on osteogenic potential of bone healing around titanium implants inserted into the tibia of rats. A blind parallel study was conducted in 45 adult male Wistar rats. Each rat received one titanium implant (4.5 x 2.2 mm) and was randomly assigned to receive subcutaneous injections, three times/week for 30 days, of the following treatments: group 1 - 40 µg/kg of PTH (1-34) (n=15); group 2 - 2 µg/kg of PTH (1-34) (n=15) and; group 3 - only the vehicle required for hormone dissolution (n=15). Thirty days after surgery, the animals were sacrificed and specimens containing the implant and the surrounding bone were removed and processed for non-decalcified sections. The sections were evaluated according to the following histometric parameters: proportion of mineralized tissue (PMT) adjacent to the implant threads (500 µm band); bone filling within the limits of the threads (BF) and; bone-to-implant contact (BIC). For the cortical region, both hormone dosages (groups 1 and 2) promoted better results, for all parameters, when compared to control group (p<0.05). Similar results were observed for the BF parameter in the cancellous region (p=0.0394). Therefore, systemic administration of PTH (1-34) stimulates bone formation around titanium implants, even at low doses.

Influence of Piezosurgery on Bone Healing around Titanium Implants: A Histological Study in Rats

Abstract The aim of this study was to evaluate histomorphometrically the influence of two techniques of dental implant site preparation on bone healing around titanium implants. Fifteen male Wistar rats (±300 g) were used in the study. Each tibia was randomly assigned to receive the implant site preparation either with a conventional drilling technique (control - DRILL group) or with a piezoelectric device (PIEZO group). The animals were sacrificed after 30 days and then the following histomorphometric parameters were evaluated (percentage) separately for cortical and cancellous regions: proportion of mineralized tissue (PMT) adjacent to implant threads (500 μm adjacent); bone area within the threads (BA) and bone-implant contact (BIC). The results demonstrated that there were no statistically significant differences between both groups for cancellous BIC (p>0.05) and cortical PMT (p>0.05). On the other hand, a higher percentage of BA was observed in the PIEZO group in the cortical (71.50±6.91 and 78.28±4.38 for DRILL and PIEZO groups, respectively; p<0.05) and cancellous regions (9.62±4.06 and 19.94±14.18 for DRILL and PIEZO groups, respectively; p<0.05). The piezosurgery also showed higher PMT values in the cancellous zone (9.35±5.54 and 18.72±13.21 for DRILL and PIEZO groups, respectively; p<0.05). However, the DRILL group presented better results for BIC in cortical region (80.42±10.88 and 70.25±16.93 for DRILL and PIEZO groups, respectively; p<0.05). In conclusion, for the implant site preparation, the piezosurgery was beneficial to bone healing rates in the cancellous bone region, while the drill technique produced better results in the cortical bone.

Resumo O objetivo deste estudo foi avaliar histomorfometricamente a influência de duas técnicas de preparo para implante dentário sobre a reparação óssea ao redor de implantes de titânio. Foram utilizados 15 ratos machos Wistar, com aproximadamente 300 g. Uma tíbia dos animais foi aleatoriamente selecionada para o preparo do leito para instalação de um implante de titânio com um motor rotatório convencional (Grupo ROTATÓRIO) e a outra com ultrassom cirúrgico piezoelétrico (Grupo PIEZO). Após 30 dias, os animais foram sacrificados e foram avaliados os seguintes parâmetros histomorfométricos (em porcentagem), separadamente, para a região cortical e medular: a proporção de tecido mineralizado (PTM) na região adjacente ao implante (500 μm adjacentes); área de tecido mineralizado (AO) dentro dos limites das roscas do implante e a extensão de tecido ósseo em contato direto (CD) com a superfície do implante. Os resultados deste estudo mostraram que não foram observadas diferenças para CD na região medular (p>0,05) e para PTM na região cortical (p>0,05). Por outro lado, um maior preenchimento das roscas foi observado quando utilizou-se ultrassom cirúrgico piezoelétrico tanto na região cortical (71,50±6,91 e 78,28±4,38 para os grupos ROTATÓRIO e PIEZO, respectivamente; p<0,05) quanto na região medular (9,62±4,06 e 19,94±14,18 para os grupos ROTATÓRIO e PIEZO, respectivamente; p<0,05). Resultados semelhantes foram observados para o parâmetro PTM na região medular (9,35±5,54 e 18,72±13,21 para os grupos ROTATÓRIO e PIEZO, respectivamente; p<0,05). No entanto, o grupo ROTATÓRIO foi superior ao grupo PIEZO em relação a CD na região cortical (80,42±10,88 e 70,25±16,93 para os grupos ROTATÓRIO e PIEZO, respectivamente; p<0,05). Pode-se concluir que, para o preparo do leito para implantes, a piezocirurgia favoreceu o reparo ósseo na região medular, enquanto a técnica convencional promoveu melhores resultados no osso cortical.

Influence of Piezosurgery on Bone Healing around Titanium Implants: A Histological Study in Rats.

The aim of this study was to evaluate histomorphometrically the influence of two techniques of dental implant site preparation on bone healing around titanium implants. Fifteen male Wistar rats (±300 g) were used in the study. Each tibia was randomly assigned to receive the implant site preparation either with a conventional drilling technique (control - DRILL group) or with a piezoelectric device (PIEZO group). The animals were sacrificed after 30 days and then the following histomorphometric parameters were evaluated (percentage) separately for cortical and cancellous regions: proportion of mineralized tissue (PMT) adjacent to implant threads (500 µm adjacent); bone area within the threads (BA) and bone-implant contact (BIC). The results demonstrated that there were no statistically significant differences between both groups for cancellous BIC (p>0.05) and cortical PMT (p>0.05). On the other hand, a higher percentage of BA was observed in the PIEZO group in the cortical (71.50±6.91 and 78.28±4.38 for DRILL and PIEZO groups, respectively; p<0.05) and cancellous regions (9.62±4.06 and 19.94±14.18 for DRILL and PIEZO groups, respectively; p<0.05). The piezosurgery also showed higher PMT values in the cancellous zone (9.35±5.54 and 18.72±13.21 for DRILL and PIEZO groups, respectively; p<0.05). However, the DRILL group presented better results for BIC in cortical region (80.42±10.88 and 70.25±16.93 for DRILL and PIEZO groups, respectively; p<0.05). In conclusion, for the implant site preparation, the piezosurgery was beneficial to bone healing rates in the cancellous bone region, while the drill technique produced better results in the cortical bone.

Changing the gingival color discrepancy induced by pigmented root using subepithelial connective tissue graft: a case report.

Metallic alloys can suffer corrosion, and metallic posts and cores used for restorative procedures may develop a blue-gray pigmentation in root dentin, which in turn changes the color of gingival tissues. Removing posts and cores may lead to root fracture, and bleaching agents have a limited effect on staining from alloy corrosion. Surgical techniques for correcting undesirable esthetic deficiencies have been investigated in the literature. This article describes the case of a patient with gingival discoloration caused by root pigmentation in the maxillary area. A subepithelial connective graft harvested from the palate was used to treat the gingival color discrepancy.