Effects of Local Low-Dose Alendronate Injections Into the Distraction Gap on New Bone Formation and Distraction Rate on Distraction Osteogenesis.

Bisphosphonates that constrain bone resorption have a direct effect on osteoclast function. In this experimental study, the effects of low-dose local alendronate injections on the distraction gap (DG) in rabbit mandible at 2 different rates were evaluated.The experimental study was conducted on 20 male, New Zealand white rabbits. The animals were divided into 3 experimental groups and 1 control group. Group 1 consisted of animals with distraction at the rate of 1 mm/day, receiving postoperative local low-dose alendronate local injections into the DG. Group 2 consisted of animals with distraction at the rate of 2 mm/day, receiving postoperative 0.75 µg/kg of alendronate local injections into the DG. Group 3 consisted of animals with distraction at the rate of 2 mm/day, receiving postoperative 0.2 mL local saline injections into the DG. Group 4 consisted of animals with distraction at the rate of 1 mm/day, receiving postoperative 0.2 mL local saline injections into the DG. All the injections were performed immediately postoperatively and for all groups at 1, 2, 3, and 4 weeks following surgery. The distraction zones were evaluated using dual-energy X-ray absorptiometry and histological analysis.Histologically, bone healing was found to be significantly accelerated in Groups 1 and 4 compared with Groups 2 and 3 (P < 0.05). Bone healing was superior in Group 1 and the difference was statistically significant compared with Group 4. There was a significant increase in mean bone mineral density in the 1 mm daily rate groups (Groups 1 and 4) compared with the 2 mm daily rate groups (Groups 2 and 3) (P < 0.05).Local low-dose alendronate injections could be an effective way for improving bone formation in distraction osteogenesis. Furthermore, the results of this study did not support the hypothesis that injections of local low-dose alendronate may allow 2 mm/day instead of 1 mm/day of elongation in the rabbit mandible.

Stress Analysis of Zygomatic Implants on the Augmented Maxillary Sinus: Is It Necessary to Graft?

PURPOSE: Zygomatic implants are becoming an ideal therapy with advanced implant-supported prosthetic treatment for the posterior atrophic maxilla. The purpose of this study is to examine the quantity and distribution of stress, which was caused by zygomatic implants placed using intrasinus method with or without augmentation to the atrophic posterior maxilla. MATERIALS & METHODS: In this study, 3-dimensional atrophic edentulous maxilla models with and without sinus augmentation are designed with computer-aided programs. Stress analysis was carried out on the created computer models for maxillary alveolar cortical bone, for cortical bone in the zygomaticomaxillary suture, and for zygomatic spongy bone at the apex of the zygomatic implant and for metal substructure of Von Misses stress data. RESULTS: Having augmented the maxillary sinus with graft, it was observed that after the loading especially in the posterior region, the tensile and compressive stresses on the alveolar crest was distributed more homogeneously and the stress generated on the cortical bone was reduced through the graft. CONCLUSION: Although zygomatic implants are graftless solutions for athrophic maxilla, sinus augmentation will be useful for bearing stress around the implants.

Comparison of Different Fixation Types Used in Unilateral Mandibular Condylar Fractures: An In Vivo Study With New Biomechanical Model.

INTRODUCTION: The aim of this in vivo study is to compare the single-titanium, double-titanium mini plate, and single resorbable plate systems used in internal rigid fixation of the unilateral mandibular condylar fractures on new design biomechanical model. METHODS: Thirty synthetic polyurethane models were used for biomechanical testing. Fracture lines were created for each model. Fragments were fixed with single-titanium plates in Group A (n = 10), double-titanium plates in Group B (n = 10), and single biodegradable plate (PPLA) in Group C (n = 10). Masticatory forces were applied to the models and the biomechanical properties of the titanium plate and screws, resorbable plate, and screws were evaluated. RESULTS: The average failure force for Group A, Group B, and Group C is 199, 324, 177N and the average bone displacement for Group A, Group B, Group C is 1.9, 0.3, 2.1 mm, respectively. DISCUSSION: Double titanium plates showed the most acceptable results in the fixation of unilateral subcondylar fractures where the single titanium and biodegradable plate systems failed to provide enough stability in unilateral subcondylar fracture fixation. Biodegradable plate systems are still not an alternative in fixation of unilateral condylar fractures.