Laura López-Marí

Histological and histomorphometric evaluation of immediate implant placement on a dog model with a new implant surface treatment

PURPOSE The aim of this study was to evaluate crestal bone resorption and bone apposition resulting from immediate post-extraction implants in the canine mandible, comparing a conditioned sandblasted acid-etched implant surface with a non-conditioned standard sandblasted implant surface. MATERIAL AND METHODS In this experimental study, third and fourth premolars and distal roots of first molars were extracted bilaterally from six Beagle dog mandibles. Each side of the mandible received three assigned dental implants, with the conditioned surface (CS) on the right side and the non-conditioned surface (NCS) on the left. The dogs were sacrificed at 2 (n=2), 4 (n=2) and 12 weeks (n=2) after implant placement. RESULTS The microscopic healing patterns at 2, 4 and 12 weeks for both implant types (CS and NCS) yielded similar qualitative bone findings. The mean crestal bone resorption was found to be greater for all implants with NCS (2.28+/-1.9 mm) than CS (1.21+/-1.05 mm) at 12 weeks. The mean percentage of newly formed bone in contact with implants was greater in implants CS (44.67+/-0.19%) than with the NCS (36,6+/-0.11%). There was less bone resorption with the CS than the NCS. CONCLUSION The data show significantly more bone apposition (8% more) and less crestal bone resorption (1.07 mm) with the CS than with the NCS after 12 weeks of healing. This CS can reduce the healing period and increase bone apposition in immediate implant placements.

Actions of melatonin mixed with collagenized porcine bone versus porcine bone only on osteointegration of dental implants

Abstract:  This study evaluated the effect of the topical application of melatonin mixed with collagenized porcine bone on the osteointegration on the rough discrete calcium deposit (DCD) surface implants in Beagle dogs 3 months after their insertion. In preparation for subsequent insertion of dental implants, lower molars were extracted from 12 Beagle dogs. Each mandible received two parallel wall expanded platform implants with a DCD surface of 4 mm in diameter and 10 mm in length. The implants were randomly assigned to the distal sites on each mandible in the molar area and the gaps were filled with 5 mg lyophilized powdered melatonin and porcine bone and collagenized porcine bone alone. Ten histological sections per implant were obtained for histomorphometric studies. After a 4‐wk treatment period, melatonin plus porcine bone significantly increased the perimeter of bone that was in direct contact with the treated implants (P < 0.0001), bone density (P < 0.0001), and new bone formation (P < 0.0001) in comparison with porcine bone alone around the implants. Melatonin plus collagenized porcine bone on DCD surface may act as a biomimetic agent in the placement of endo‐osseous dental implants and enhance the osteointegration. Melatonin combined with porcine bone on DCD implants reveals more bone in implant contact at 12 wk (84.5 ± 1.5%) compared with porcine bone alone treated area (67.17 ± 1.2%).

Melatonin stimulates the growth of new bone around implants in the tibia of rabbits

Abstract:  This study evaluated the effect of the topical application of melatonin in accelerating bone formation associated with implants 2 months after their application to the tibiae of rabbits. Twenty New Zealand rabbits were used. Twenty implants treated with melatonin and 20 control implants without melatonin were placed in the proximal metaphyseal area of each tibia. Studies of new bone formation were subsequently made at 15, 30, 45 and 60 days. Cortical width and cortical length of new bone formation were measured. Following implantation, an anteroposterior and lateral radiologic study was carried out. Collected samples were sectioned at 5 μm and stained using hematoxylin–eosin, Masson’s trichromic and Gordon‐Switt reticulin stains. After a 60 day treatment period, melatonin increased the length of cortical bone (95.13 ± 0.42%) versus that around control implants (62.91 ± 1.45%). Related to the perimeter of cortical bone of the tibiae, melatonin induced new bone 88.35 ± 1.56% versus 60.20 ± 1.67% in the control implants. Melatonin regenerated the width and length of cortical bone around implants in tibiae of rabbits more quickly than around control implants without the addition of melatonin.

Melatonin plus porcine bone on discrete calcium deposit implant surface stimulates osteointegration in dental implants

Abstract:  The aim of this study was to evaluate the effect of the topical application of melatonin mixed with collagenized porcine bone to accelerate the osteointegration on the rough discrete calcium deposit (DCD) surface implants in Beagle dogs 3 months after their insertion. In preparation for subsequent insertion of dental implants, lower premolars and molars were extracted from 12 Beagle dogs. Each mandible received three parallel wall implants with discrete calcium deposit (DCD) surface of 4 mm in diameter and 10 mm in length. The implants were randomly assigned to the distal sites on each side of the mandible in three groups: group I implants alone, group II implants with melatonin and group III implants with melatonin and porcine bone. Prior to implanting, 5 mg lyophylized powdered melatonin was applied to one bone hole at each side of the mandible. None was applied at the control sites. Ten histological sections per implant were obtained for histomorphometric studies. After a 4‐wk treatment period, melatonin significantly increased the perimeter of bone that was in direct contact with the treated implants (P < 0.0001), bone density (P < 0.0001), new bone formation (P < 0.0001) in comparison with control implants. Topical application of melatonin on DCD surface may act as a biomimetic agent in the placement of endo‐osseous dental implants and enhance the osteointegration. Melatonin combined with porcine bone on DCD implants reveals more bone to implant contact at 12 wk (84.5 ± 1.5%) compared with melatonin treated (75.1 ± 1.4%) and nonmelatonin treated surface implants (64 ± 1.4%).

Crestal bone loss evaluation in osseotite expanded platform implants: a 5‐year study

OBJECTIVE The aim of this prospective clinical study was to evaluate the survival rates at 5 years of expanded platform implants placed in the anterior zone of the maxilla and immediately restored with single crowns. MATERIALS AND METHODS Implants incorporating the platform-switching concept were placed in fresh extraction sockets in the maxillary arch, with each patient receiving a provisional restoration immediately after implant placement. After 15 days, final screwed restorations were inserted. Mesial and distal bone heights were evaluated using digital radiography on the day following implant placement and at 1, 3, 6, 9, 12, 24, 36 months and 5 years. Primary stability was measured with resonance frequency analysis (RFA) using the Osstell Mentor device. Sixty-four implants were placed in 32 men and 32 women ranging in age between 29 and 60 (mean: 39.64 ± 5.16 years). RESULTS Mean mesial bone loss was 0.08 mm (SD 0.42). Mean distal bone loss was 0.14 mm (SD 0.56). Over the course of the 5 years, the mean RFA value was 72.5 ± 3.1 SD. CONCLUSION The platform-switched implants remained stable over the course of 5 years and had an overall survival rate of 97.1%.

New bone formation in bone defects after melatonin and porcine bone grafts: experimental study in rabbits

OBJECTIVE The aim of this study was to evaluate the effect of the topical application of melatonin compared with collagenized porcine bone grafts to accelerate bone formation 2 months after their insertion in tibiae rabbits. MATERIAL AND METHODS Twenty New Zealand rabbits weighing 3,900-4,500 g were used. Twenty collagenized porcine bone (MP3) grafts, twenty melatonin-impregnated bone grafts, and twenty control areas were placed in the proximal metaphyseal area of both rear tibias. Four groups were formed according to the moment in which animal killing was carried out: Group I (15 days), Group II (30 days), Group III (45 days) and Group IV (60 days). Cortical width and cortical length of bone formation was measured. Following implantation, an anteroposterior and lateral radiological study was carried out. Samples were sectioned at 5 μm and stained using hematoxylin-Eeosin, Massons trichromic, and Gordon-Switt reticulin stains. RESULTS After 60 days of treatment period, melatonin increased the length of cortical bone formation 99.03 ± 0.61% like control 98.90 ± 3.82% compared with porcine bone 92.73 ± 1.08%. Related to perimeter of cortical bone of the tibiae melatonin new bone was 98.35 ± 1.14% like control 98.0 ± 1.43% more than porcine bone 92.05 ± 1.03%. Histomorphometric values related to porcine bone were connective tissue 49.16 ± 2.4%, graft material (MP3) 23.52 ± 2.3%, and new bone formation 27.32 ± 1.4% compared with test group with melatonin 24.5 ± 1.2%, connective tissue 45.1 ± 1.2%, and new bone formation of 30.4 ± 1.0%. CONCLUSION Melatonin has proven to regenerate the width and length of cortical bone in tibiae rabbits more quickly than collagenized porcine bone. Melatonin acts as a bone stimulator compared with porcine bone and control sites.

Biological response to porcine xenograft implants: an experimental study in rabbits

Purpose: The aim of this study was to evaluate the effect of a new porcine biomaterial and collagen paste in 20 New Zealand rabbits. Materials and Methods: Forty implants using a porcine xenograft made up of 80% corticocancellous collagenated bone particles of ⩽300 &mgr;m in size were placed in the proximal metaphyseal area of both tibiae. Four periods of time were formed: 1h, 5, 8, and 15 months. After implantation, an anteroposterior and lateral radiological study was carried out. Samples were sectioned at 5 &mgr;m and stained using hematoxylin-eosin, Massons trichromic, and Gordon-Switt reticulin stains. Results: These results confirmed the biocompatibility of this porcine biomaterial-collagen paste; only a few, occasional macrophages and scattered lymphocytes were observed. No fibrosis was observed between the implants and the bone. Moreover, the material was osteoconductive acting as a “scaffold” for bone cells, and there was a progressive increase in bone growth in and around the implants. Conclusion: This new porcine biomaterial-collagen paste seemed to be biocompatible, bioresorbable, and osteoconductive.