Francesco Pieri

Effect of Mesenchymal Stem Cells and Platelet-Rich Plasma on the Healing of Standardized Bone Defects in the Alveolar Ridge: A Comparative Histomorphometric Study in Minipigs

PURPOSE The purpose of this study was to test the effect of the combination of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) incorporated into a fluorohydroxyapatite (FHA) scaffold on bone regeneration in cylindrical defects in the edentulous mandibular ridge of minipigs. MATERIALS AND METHODS Two mandibular premolar teeth were extracted bilaterally in 8 adult minipigs. After 2 months, 4 standardized defects of 3.5 mm diameter and 8 mm depth were created in each root site. The defects were randomly grafted with autogenous mandibular bone, FHA alone, PRP-FHA, or MSCs-PRP-FHA. A resorbable collagen membrane was placed over the defect area and the flaps were sutured. The animals were sacrificed 3 months later and biopsy samples were taken from the defect sites for histologic and histomorphometric assessment. RESULTS There was no evidence of inflammation or adverse tissue reaction with either treatment. MSCs-PRP-FHA-treated sites showed new vital bone between residual grafting particles. PRP-FHA- and FHA-treated sites showed residual particles in a background of marrow soft tissue with a moderate quantity of newly formed bone. Autogenous bone (46.97%) and MSCs-PRP-FHA (45.28%) produced a significantly higher amount of vital bone than PRP-FHA (37.95%), or FHA alone (36.03%). Further, the MSCs-PRP-FHA-treated defects showed a significantly higher percentage of contact between graft particles and newly formed bone compared with PRP-FHA and FHA group (59.23% vs 48.37% and 46.43%, respectively). CONCLUSIONS Our results suggest that, in this animal model, the addition of MSCs to PRP-FHA enhances bone formation after 3 months.

Dose-dependent effect of adipose-derived adult stem cells on vertical bone regeneration in rabbit calvarium.

Previous in vivo studies have shown a limited potential for vertical bone regeneration using osteoconductive scaffolds alone. In the present study, we investigated whether the association of adipose-derived adult stem cells (ASCs) with anorganic bovine bone (ABB) scaffold improved bone formation and implant osseointegration in a vertical guided bone regeneration model. Two pre-formed titanium domes were placed on the calvaria of 12 rabbits. Four treatment modalities were evenly distributed among the 24 domes: ABB alone, and ABB containing 3 x 10(5), 3 x 10(6), or 3 x 10(7) cells/graft. After 1 month, the domes were removed and one titanium implant was placed into each augmented site. One month after the second operation, the animals were killed and biopsy specimens were examined by histomorphometric and micro-CT analyses. Results indicated that at all concentrations, the ASC-loaded groups showed significantly more new bone formation and higher mean values of bone-implant contact and bone density inside threads than the ABB group. Furthermore, ASCs demonstrated a dose-response relationship, with the highest dose chosen inducing more robust bone regeneration. This study suggests that the delivery of ASCs on ABB might effectively increase vertical bone regeneration and implant osseointegration, versus ABB alone.

Mesenchymal stem cells and platelet-rich plasma enhance bone formation in sinus grafting: a histomorphometric study in minipigs

OBJECTIVES Autologous, allogenic, and alloplastic materials for sinus augmentation have specific drawbacks, which has stimulated an ongoing search for new materials and tissue-engineering constructs. We investigated whether mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) seeded on a fluorohydroxyapatite (FH) scaffold can improve bone formation and bone-to-implant contact (BIC) in maxillary sinus grafting. MATERIAL AND METHODS Bilateral sinus augmentation procedures were performed in eight minipigs. MSCs, PRP, and FH scaffold (test site) or FH alone (control site) were grafted in each maxillary sinus. Distal to the osteotomy, one dental implant per sinus was placed in the grafting material through the facial sinus wall. The animals were killed 3 months after grafting, and block sections of the implant sites were harvested and prepared for histomorphometric analysis. RESULTS After 12 weeks, a significant increase in bone formation occurred in the test sites compared with the control sites (42.51%versus 18.98%; p=0.001). In addition, BIC was significantly greater in the test sites compared with the control sites in the regenerated area (23.71%versus 6.63%; p=0.028). CONCLUSIONS These findings show that sinus augmentation with MSCs-PRP, combined with FH may enhance bone formation and osseointegration of dental implants compared with FH alone in minipigs.

Problems with dental implants that were placed on vertically distracted fibular free flaps after resection: A report of six cases

We report the clinical outcome of dental implants placed on vertically distracted fibular free flaps that were used to reconstruct maxillary and mandibular defects after resection. Distraction osteogenesis (DO) of fibular free flaps was used for six patients (5 men, 1 woman) a mean of 19 months (range 11-38) after 5 mandibular and 1 maxillary reconstructions. A mean of 5 months (range 2-11) after removal of the distractor, 35 implants were inserted and loaded with implant-supported fixed prostheses. The mean (range) follow-up period was 39 (17-81) months. The course of the DO and the clinical and radiographic outcomes of the implants were assessed. Of six vertically distracted fibular free flaps, there was one case of vector lingual tipping during the consolidation phase and a fracture of the basal fibular cortex that necessitated additional grafting with iliac bone to stabilise the distracted area. The mean (range) vertical bone gain was 14 (12-15) mm. Four of 35 implants (11%) failed during the follow-up period. The mean peri-implant bone resorption was 2.5mm. Cumulative implant survival was 31/35 (89%) and survival after loading 31/33 (94%). Distraction osteogenesis of fibular free flaps caused a remarkable number of complications and pronounced resorption of bone around the implants, probably as a result of the formation of granulomatous tissue; a careful peri-implant follow-up and the maintenance of oral hygiene are essential.

Esthetic outcome and tissue stability of maxillary anterior single-tooth implants following reconstruction with mandibular block grafts: a 5-year prospective study.

PURPOSE The aim of this prospective study was to evaluate the hard and soft tissue stability and esthetic outcomes of single-tooth implants placed in the anterior atrophic maxilla, following augmentation with mandibular block grafts covered with bovine hydroxyapatite and a resorbable collagen membrane, over a 5-year period. MATERIALS AND METHODS Patients with a bony deficiency of ≥ 3 mm horizontally and ≤ 3 mm vertically were treated consecutively with reconstructive procedures and implant placement 6 months afterward. Alveolar ridge dimensions were measured before and after augmentation using computed tomography. Clinical and radiographic measurements of soft and hard tissue levels and esthetic parameters (pink esthetic score [PES]) were performed annually to assess treatment outcomes. RESULTS Twenty-nine patients were treated. One patient had partial graft exposure after 1 month that required regrafting at the time of implant placement. Mean bone gain was 4.23 ± 0.69 mm horizontally and 1.71 ± 0.75 mm vertically. The implant cumulative success rate was 100%, according to the criteria of Albrektsson et al. Mean crestal bone resorption after 5 years was low (0.61 ± 0.33 mm). Moderate recession of the facial mucosa (-1.12 ± 0.4 mm) was observed during the study period, while mesial and distal papilla heights increased slightly (0.13 ± 0.17 and 0.19 ± 0.37 mm, respectively). Mean PES ratings remained stable, varying from 9.07 ± 1.49 at the moment of definitive crown delivery to 8.61 ± 1.55 at 5 years. Only two cases (7%) were considered slightly below the defined threshold (PES = 8) of marginal esthetic acceptability. CONCLUSIONS This study demonstrated that implants placed in anterior atrophic maxillae augmented with mandibular block grafts showed stable hard and soft tissue levels and reasonable esthetic outcomes over the medium term, although ongoing recession of the facial mucosa was observed.

Augmentation of the floor of the maxillary sinus with recombinant human bone morphogenetic protein-7: a pilot radiological and histological study in humans.

The aim of this study was to evaluate the quantity and quality of bony regeneration after we had used recombinant human bone morphogenetic protein-7 (rhBMP-7 to augment the floor of the maxillary sinus. Nine consecutive patients with bilateral posterior maxillary atrophy who required augmentation of the sinus for interposition of implants were treated simultaneously with rhBMP-7 (Osigraft) with deproteinised bone substitute (0.5 g on the test side) and with deproteinised bone alone (2.0 g on the control side). Computed tomographic images preoperatively, immediately postoperatively, and at 4 months postoperatively showed a mean (SD) postoperative gain of 10.8 (3.0) mm on the test side and of 10.2 (1.8) mm on the control side. Histological and histomorphometric analyses of biopsy specimens showed that there was significantly more new bone on the control side (19.9 (6.8)%) than on the test side (6.6 (4.8)%). In this pilot controlled trial of the use of rhBMP-7, histological analyses showed that it resulted in the formation of less bone than treatment with inorganic bovine hydroxyapatite.

Immediate functional loading of dental implants supporting a bar-retained maxillary overdenture: preliminary 12-month results.

BACKGROUND The present study evaluated the efficacy of a treatment consisting of placing and immediately loading implants with a bar-retained overdenture in edentulous maxillae. METHODS Twenty-two consecutive patients were treated with four or five implants rigidly connected with a bar, which were then loaded with a maxillary overdenture within 48 hours post-surgery. The patients were followed clinically and radiographically for 1 year after loading. The implant outcome with regard to survival and success was analyzed. Visual analog scale questionnaires were used to record patient function and satisfaction before and after implant treatment. RESULTS Of the 103 implants, three failed within 1 year. Two implants, although integrated, presented with marginal bone resorption (MBR) values higher than those proposed for successful implants. Cumulative survival and success rates of implants were 97.1% and 95.2%, respectively. The average MBR after 1 year was low (0.78 +/- 0.79 mm). The main prosthetic complication was the frequent need for complete relining of the prosthesis in the initial weeks after loading (27.2%). The questionnaire revealed a significant increase in all comfort, functional, and esthetic parameters (Friedman test; P <0.0001), except in the cleaning feasibility category; a significant decrease in satisfaction was observed in this category (Friedman test; P <0.05), indicating the difficulty patients had in maintaining a high level of oral hygiene. CONCLUSION These preliminary results suggest that immediate loading of multiple implants supporting a bar-retained overdenture may represent a predictable treatment option for the rehabilitation of the edentulous maxilla.

Immediate fixed implant rehabilitation of the atrophic edentulous maxilla after bilateral sinus floor augmentation: a 12-month pilot study.

PURPOSES The aims of this study were to evaluate a surgical/prosthetic protocol for the immediate rehabilitation of the augmented edentulous maxilla, and to compare the outcomes of implants placed in grafted (test group) versus native (control group) sites in the same patients. MATERIALS AND METHODS Twenty patients were included in the study. Each patient was treated with a bilateral sinus augmentation procedure using a 50:50 composite graft of autogenous mandibular bone and bovine hydroxyapatite. Four to 5 months later, 155 implants (90 test and 65 control) were placed and restored with screw-retained fixed definitive prostheses supported by titanium frameworks within 1 week. All patients were followed for 1 year. Implant stability quotient (ISQ) measurements and radiographic evaluation of the marginal bone resorption (MBR) were performed. RESULTS Two test implants failed in two patients, giving a cumulative 1-year success rate of 98.7%; the prostheses success rate was 100%. Insertion torque and ISQ values for test implants were significantly lower than those for control implants (unpaired t-test, p < .0001). The mean MBR around control and test implants at the 1-year evaluation were similar (0.47 ± 0.25 mm and 0.43 ± 0.21 mm, respectively). CONCLUSIONS The combination of implants placed in sinus-grafted and native sites can be immediately loaded with a fixed full-arch prosthesis and yield short-term successful outcomes.

Narrow- (3.0 mm) Versus Standard-Diameter (4.0 and 4.5 mm) Implants for Splinted Partial Fixed Restoration of Posterior Mandibular and Maxillary Jaws: A 5-Year Retrospective Cohort Study

BACKGROUND Evidence concerning predictability of narrow-diameter implants (NDIs) (<3.3 mm) to restore partially edentulous posterior maxillary and mandibular areas is limited. The aim of this study is to compare the 5-year outcomes of NDIs (3.0 mm) and standard-diameter implants (SDIs) (4.0 to 4.5 mm) supporting fixed partial dentures (FPDs) in posterior mandibular and maxillary jaws. METHODS All patients treated with at least two adjacent NDIs or SDIs according to available bone thickness and with a minimum follow-up of 5 years after placement were invited to undergo a clinical and radiologic examination. Outcome measures were implant and FPD failures, biologic and prosthetic complications, and marginal bone loss. RESULTS A total of 107 out of 127 patients attended the examination: 49 (113 implants) of the NDI group, and 58 (126 implants) of the SDI group. Two NDIs failed in one patient versus four SDIs in four patients (P = 0.37). One FPD failed in the NDI group versus two FPDs in the SDI group (P >0.99). Nine biologic complications occurred in the NDI group and twelve in the SDI group (P = 0.81). Twelve prosthetic complications occurred in the NDI group and only two in the SDI group (P = 0.001). Peri-implant marginal bone loss at 5 years was 0.95 ± 0.84 mm for the NDI group and 1.2 ± 0.86 mm for the SDI group (P = 0.06). CONCLUSION Five-year data indicate that FPD treatment in posterior mandibular and maxillary jaws with NDIs was as reliable as with SDIs, although NDIs showed a higher risk of prosthetic complications.

Clinical, esthetic, and radiographic evaluation of small-diameter (3.0-mm) implants supporting single crowns in the anterior region: a 3-year prospective study.

Fifty patients underwent single-tooth replacement in the maxillary and mandibular incisor area using two-piece 3.0-mm-diameter implants. Clinical and radiographic measurements of soft and hard tissue levels and esthetic parameters (pink esthetic score/white esthetic score [PES/WES]) were assessed at 3 years. No implant failed (success rate: 100%), and facial soft tissues and marginal bone levels remained stable throughout the study period. The mean total PES/WES was high (14.1 ± 1.75), and only one implant demonstrated an unfavorable esthetic outcome (PES/WES = 10). The use of 3.0-mm-diameter implants appears to be a viable treatment procedure in the medium term for single-tooth anterior restorations with limited dimensions.