María Peñarrocha Diago

Ultrastructural study by backscattered electron imaging and elemental microanalysis of biomaterial-to-bone interface and mineral degradation of bovine xenografts in maxillary sinus floor elevation.

OBJECTIVES The aim of this study was to perform an ultrastructural study of the bone-to-biomaterial interface and biomaterial mineral degradation in retrieved bone biopsies following maxillary sinus augmentation using bovine xenografts (Endobon(®)) in 15 clinical cases. MATERIALS AND METHODS Nine months after sinus lifting, bone cores were harvested from the maxillary sinus. The specimens were processed for observation under a scanning electron microscope with backscattered electron imaging (SEM-BSE). In addition, chemical analysis and elemental mapping of the mineral composition were generated using a microanalytical system based on energy-dispersive X-ray spectrometry (EDX). RESULTS No clinical complications occurred during surgery. Scanning electron microscopy revealed that newly formed bone was closely attached to the xenograft. Elemental analysis showed a significantly high Ca/P ratio in the residual biomaterials (3.031 ± 0.104) compared with the interface (2.908 ± 0.115) and new bone (2.889 ± 0.113), which suggests that there may be a gradual diffusion of Ca ions from the biomaterial into the newly forming bone at the interface as part of the biomaterials resorption process. EDX analysis of the residual bovine biomaterial showed particle categories with different mean Ca/P ratios according to size, pointing to different stages of the resorption process. CONCLUSIONS The biomaterial proved to be biocompatible and osteoconductive when used as a bone substitute for maxillary sinus elevation. The grafting material used is not a completely resorbable material over the time period covered by this study.

Tilted Implants for the Restoration of Posterior Mandibles With Horizontal Atrophy: An Alternative Treatment

PURPOSE Horizontal atrophy in the posterior mandible presents serious limitations on conventional implant placement. The purpose of this study was to evaluate the use of tilted implants angled in a buccolingual direction for restoring atrophic posterior mandibular sectors. MATERIALS AND METHODS A cohort study was performed of 25 patients who had partial prostheses supported by more than 1 implant (≥ 1 tilted and 1 axial implant) to restore molar areas in the mandible. When the bone thickness was at least 5 mm, axial implants were placed; when the alveolar ridge was narrower, the implant was placed with tilted angulation. The beds for these tilted implants were prepared using a lingual approach, tipping the implant apex toward the vestibule. Twelve months after loading, bone loss was evaluated and the success rates of the tilted and axial implants were calculated. RESULTS The study included 20 women and 5 men (mean age, 54.8 yr) who received 67 implants in the posterior mandibular sectors. Thirty-nine implants were placed with a buccal angulation and 28 implants were placed vertically. Mean bone losses of 0.59 ± 0.26 mm among the tilted implants and 0.48 ± 0.34 mm among the axial implants were observed 1 year after loading. The success rate of the tilted implants was 94.9%, and that of the axial implants was 100%. No significant differences in success rates or in bone loss between the tilted and axial implants were found at 12 months after loading. CONCLUSIONS Twelve months after loading, tilted implants provided good results for the restoration of posterior mandibles with horizontal atrophy and no significant differences in success rates or marginal bone loss between tilted and axial implants were observed.