A Pilot Study on the Efficacy of a Treatment Algorithm to Detoxify Dental Implant Surfaces Affected by Peri-implantitis.

This in vitro pilot study was performed to determine whether a treatment algorithm including mechanical debridement, followed by air powder abrasion with glycine, followed by citric acid conditioning with vigorous flushing of the surface with sterile water after each step, is capable of decontaminating an infected implant surface. A total of 14 dental implants that were deemed hopeless due to advanced peri-implantitis were extracted. Of these, 6 implants served as tests and had their exposed surfaces treated with the decontamination protocol, 6 served as untreated controls, and 2 were mechanically treated only, followed by rubbing the surface with sterile saline. All implants were placed in culture with human osteoprogenitor cells for 72 hours, and evaluation was performed using scanning electron microscopy. The 6 test implants all demonstrated attachment and proliferation of the normal human osteoprogenitor cells on their prior exposed and decontaminated surfaces. All of the untreated control and the mechanically debrided, sterile water-treated implants failed to demonstrate this same success. The results suggest that this protocol can decontaminate an implant surface affected by peri-implantitis. Further studies are warranted to determine if this technique would demonstrate similar success over a greater number of implants and whether this outcome may occur in humans.

Shear bond strength of an experimental composite bracket.

OBJECTIVE: The in vitro shear bond strength of MZ100 brackets (an experimental composite bracket developed by the Dental Biomaterial Laboratory at Boston University) and the effect of different treatment methods on these brackets were evaluated. MATERIALS AND METHODS: As the bonding substrates, 80 Vitablocs® Mark II (Vident, Brea, CA, USA) were chosen. Three treatment methods were employed on 60 MZ100 bracket bases (20 brackets per treatment): silane coupling agent (Porcelain Primer; Ormco, Orange, CA, USA), sandblasting (Basic Professional Model Sandblaster; Renfert GmbH, Germany), and non-treatment. Two different orthodontic adhesives were also used: Blugloo™ (Ormco, Orange, CA, USA) and Enlight™ (Ormco, Orange, CA, USA). Twenty metal brackets were used as controls. Shear bond strength tests were performed after sample preparation and bracket bonding. RESULTS: The mean shear bond strength of non-treated MZ100 brackets bonded with Enlight™ had the lowest value (7.9 MPa), while that of sandblasted MZ100 brackets bonded with Blugloo™ showed the highest value (17.9 MPa). The mean shear bond strength of non-treated MZ100 brackets was significantly lower than that of the other groups (p<0.05). The mean shear bond strength of sandblasted MZ100 brackets bonded with Blugloo™ was significantly higher than that of those bonded with Enlight™ (p<0.05). With the exception of the silane-Blugloo™ group, the treated MZ100 brackets demonstrated shear bond strengths that did not significantly differ from metal brackets. CONCLUSION: The use of sandblasting and silane coupling agent significantly increases the shear bond strength of the MZ100 brackets to values resembling those of metal brackets.

Maxillary sinus floor elevation using a tissue engineered bone complex with BMP-2 gene modified bMSCs and a novel porous ceramic scaffold in rabbits.

OBJECTIVES: To study the effects of maxillary sinus floor elevation by a tissue engineered bone complex with bone morphogenetic protein-2 (BMP-2) gene modified bone marrow stromal cells (bMSCs) and a novel porous ceramic scaffold (OsteoBone) in rabbits. MATERIALS AND METHODS: bMSCs derived from New Zealand rabbit bone marrow were cultured and transduced with adenovirus AdBMP-2 and with AdEGFP gene (without BMP-2 gene sequence) as a control, respectively, in vitro. These bMSCs were then combined with OsteoBone scaffold at a concentration of 2 x 10(7)cells/ml and used to elevate the maxillary sinus floor in rabbits. Eight rabbits were randomly allocated into groups and sacrificed at weeks 2 and 4. For each time point, 8 maxillary sinus floor elevation surgeries were made bilaterally in 4 rabbits for the two groups (n=4 per group): group A (AdBMP-2-bMSCs/material) and group B (AdEGFP-bMSCs/material). All samples were evaluated by histologic and histomorphometric analysis. RESULTS: The augmented maxillary sinus height was maintained for both groups over the entire experimental period, while new bone area increased over time for group A. At week 4 after operation, bone area in group A was significantly more than that in group B (P<0.05), and was more obviously detected in the center of the elevated space. Under a confocal microscope, green fluorescence in newly formed bone was observed in the EGFP group, which suggests that those implanted bMSCs had contributed to the new bone formation. CONCLUSION: bMSCs modified with AdBMP-2 gene can promote new bone formation in elevating the rabbit maxillary sinus. OsteoBone scaffold could be an ideal carrier for gene enhanced bone tissue engineering.

Maxillary sinus floor elevation using a tissue-engineered bone complex with OsteoBone and bMSCs in rabbits.

OBJECTIVES: To evaluate the effects of maxillary sinus floor elevation by a tissue-engineered bone complex with OsteoBone(trade mark) and bone marrow stromal cells (bMSCs) in rabbits. MATERIAL AND METHODS: Autologous bMSCs from adult New Zealand rabbits were cultured and combined with OsteoBone(trade mark) at a concentration of 20 x 10(6) cells/ml in vitro. Twenty-four animals were used and randomly allocated into groups. For each time point, 16 maxillary sinus floor elevation surgeries were made bilaterally in eight animals and randomly repaired by bMSCs/material (i.e. OsteoBone), material, autogenous bone and blood clot (n=4 per group). A polychrome sequential fluorescent labeling was also performed post-operatively. The animals were sacrificed 2, 4 and 8 weeks after the procedure and evaluated histologically as well as histomorphometrically. RESULTS: New bone area significantly decreased from weeks 2 to 8 in the blood clot group, while bone area in the autologous bone reduced from weeks 4 to 8. In both groups, a significant amount of fatty tissue appeared at week 8. Accordingly, augmented height in both groups was also significantly decreased from weeks 2 to 8. The bone area in the material-alone group as well as in the bMSCs/material group, on the other hand, increased over time. Significantly more newly formed bone area and mineralization was observed in the center of the raised space in the bMSCs/material group than in the material-alone group. The augmented height was maintained in these two groups throughout the course of this study. CONCLUSION: These results suggest that OsteoBone can successfully be used as a bone graft substitute and that the combination of this material with bMSCs can effectively promote new bone formation in sinus elevation.