A microcomputed tomography analysis of bone tissue after vertical ridge augmentation with non-resorbable membranes versus resorbable membranes and titanium mesh in humans.

PURPOSE: Guided bone regeneration is a frequently used surgical procedure for hard tissue reconstruction when horizontal and or/vertical augmentation are needed. The treatment concept is based on the application of occlusive membranes like non-resorbable membranes or titanium mesh plus resorbable membranes. However, there are no studies comparing the microcomputed tomography results for bone obtained using these two procedures, and this was the purpose of the present study. MATERIALS AND METHODS: A total of 40 patients with vertical posterior bone mandibular atrophy were randomly assigned to group A (guided bone regeneration with titanium-reinforced polytetrafluoroethylene membrane and simultaneous implant placement) or group B (guided bone regeneration with titanium mesh and collagen membrane and simultaneous implant placement). Tissue biopsy specimens were obtained from augmented sites after 9 months for microcomputed tomography analysis of volume of interest. Bone volume (BV/TV), biomaterial volume (MatV/TV), soft tissue volume (StV/TV), trabecular thickness (TbTh), trabecular number (TbN) and trabecular separation (TbSp) were measured. The correlation between regenerated bone and native bone was also evaluated. STATA software (StataCorp, College Station, TX, USA) was utilised for statistical analysis (significance α = 0.05). RESULTS: In group A, the values of BV/TV, MatV/TV and StV/TV in regenerated bone were 28.8%, 8.9% and 62.4%, respectively. In group B, the values of BV/TV, MatV/TV and StV/TV were 30.0%, 11.0% and 59.0%, respectively. No statistical differences were found between the two groups for any of the variables (P < 0.05). In both groups, considerable differences were noted between regenerated and native bone (P > 0.05), with a slight correlation between the microcomputed tomography parameters that suggests that native bone influences the quality of regenerated bone. CONCLUSIONS: Based on microcomputed tomography analysis, both surgical approaches facilitated the obtention of approximately 30% of newly formed bone with the same microarchitecture. Native bone influences the quality and microarchitecture of the obtained bone, irrespective of the technique used.

A Proposal of Pseudo-periosteum Classification After GBR by Means of Titanium-Reinforced d-PTFE Membranes or Titanium Meshes Plus Cross-Linked Collagen Membranes.

After guided bone regeneration (GBR) with different devices, a layer of connective tissue called pseudo-periosteum can be observed above the newly formed bone. The aim of this study is to evaluate the clinical and histologic features and to suggest a classification of this connective tissue after GBR with nonresorbable membranes or titanium (Ti)-mesh plus resorbable membranes. Forty patients with partial edentulism in the posterior mandible were randomized into two groups: 20 patients were treated by means of Ti-reinforced dense polytetrafluoroethylene (d-PTFE) membrane (group A), while the other 20 patients were treated with Ti-mesh and a cross-linked collagen membrane (group B). After 9 months and during re-opening surgery, bone density and pseudo-periosteum type were recorded. Pseudo-periosteum was classified into Type 1 (no tissue or tissue < 1 mm); Type 2 (regular tissue between 1 and 2 mm); and Type 3 (irregular tissue or tissue > 2 mm). Histologic analyses were performed to identify the features of pseudo-periosteum. Out of 40 patients, 36 (n = 19 in Group A; n = 17 in Group B) with 99 implants were analyzed after GBR and according to the study protocol. The vertical bone gain was 4.2 ± 1.0 mm in Group A and 4.1 ± 1.0 mm in Group B. Group A had a higher bone density and greater amounts of type 1 periosteum than Group B (P = .01 for both). The preliminary results of this study show that both d-PTFE membranes and Ti-mesh plus collagen membranes are two valid options for bone augmentation in the mandible. However, nonresorbable membranes achieve higher bone density and a thinner pseudo-periosteum layer above the newly formed bone.

Complex Regional Pain Syndrome Type I, a Debilitating and Poorly Understood Syndrome. Possible Role for Pulsed Electromagnetic Fields: A Narrative Review.

BACKGROUND: Complex regional pain syndrome type I (CRPS-I), also called algodystrophy, is a complex syndrome characterized by limb pain, edema, allodynia, hyperalgesia and functional impairment of bone with a similar clinical picture of osteoporosis, including an increased release of various pro-inflammatory neuropeptides and cytokines. Several treatments have been proposed for CRPS-I, but due to the poor outcome of conventional drugs and the invasiveness of some techniques, expectations are now directed towards new resources that could be more effective and less invasive. OBJECTIVE: In the light of preclinical evidence, which underlined pulsed electromagnetic fields' (PEMFs) properties on osteoblasts (OBs), osteoclasts (OCs), and pathologies with an inflammatory profile, the present review aims to investigate whether there is a rationale for the use of PEMFs, as a combined approach, in CRPS-I. STUDY DESIGN: This review analyzed the 44 in vitro and in vivo studies published in the last decade that focused on 2 main aspects of CRPS-I: local osteoporosis (OP) and inflammation. SETTING: Not applicable. METHODS: This review includes in vitro and in vivo studies found with a PubMed and Web of Knowledge database search by 2 independent authors. The limits of the search were the publication date between January 1, 2006, and January 1, 2016, and English language. In detail, the search strategy was based on: 1) CRPS-I or algodystrophy; 2) OP, OCs, and OBs; and 3) inflammatory aspects. RESULTS: The included studies looked at the relationship between PEMFs and OCs (2 in vitro studies), osteoporotic animal models (8 in vivo studies), OBs (20 in vitro studies), inflammatory cytokines, and reactive oxygen species. They also tried to define the molecular cell pathways involved (5 in vivo and 9 in vitro studies on inflammatory models). It was observed that PEMFs increased OC apoptosis, OB viability, bone protein and matrix calcification, antioxidant protein, and the levels of adenosine receptors, while it decreased the levels of pro-inflammatory cytokines. LIMITATIONS: Data from clinical trials are scarce; moreover, experimental conditions and PEMF parameters are not standardized. CONCLUSIONS: The present review underlined the rationale for the use of PEMFs in the complex contest of CRPS-I syndrome, in combination with conventional drugs. Key words: Complex regional pain syndrome type I, algodystrophy, pulsed electromagnetic field stimulation, osteoporosis, inflammation, osteoclasts, osteoblasts, pain.

Raman spectroscopic investigation on the molecular structure of apatite and collagen in osteoporotic cortical bone.

This study employed highly spectrally resolved Raman spectroscopy to examine the molecular composition of cortical bone tissue obtained from murine females in their healthy and ovariectomy- (OVX-) induced osteoporotic states. The aim of the study was to identify structural differences at the molecular scale both in apatite mineral and collagen fibrils between the two groups of samples. Raman spectroscopy was used to determine the chemical composition of cortical bone in regions including characteristic bands of both bone mineral and bone matrix. The results demonstrated that the mineral apatite of bone did not undergo significant amorphization in its diseased state, with the Raman microprobe also failing in recognizing a direct role of carbonate content in the embrittlement of OVX-diseased bone. On the other hand, complex off-stoichiometry variations could be detected in the columnar Ca-structure of the bony hydroxyapatite according to morphological variations of the Raman band belonging to the symmetric phosphate stretching (A1) band at ~959cm-1. A fundamental role was also recognized for collagen quality on the process of bone embrittlement. The so-called matrix maturity ratio, as systematically measured on Raman spectra in the Amide I region, increased with statistical significance in OVX-treated samples as compared to control samples. An 8% increase could be associated to a 115% increase in elastic stress intensification in the mineral phase of OVX-diseased tissue as compared to the control one, thus proving a degradation in the (elastic) energy-dissipative capacity of a diseased bone matrix.

Peripheral Blood Mononuclear Cells Spontaneous Osteoclastogenesis: Mechanisms Driving the Process and Clinical Relevance in Skeletal Disease.

In vitro peripheral blood mononuclear cells differentiate into osteoclasts under the influence of osteoclast-stimulating factors. However, accumulating evidence suggests spontaneous osteoclasts formation and activity in patients affected by local or systemic bone remodeling diseases in comparison with healthy controls. Therefore, within this review, we summarize the studies where spontaneous osteoclastogenesis of peripheral blood mononuclear cells was observed in pathological conditions of the skeletal system. We indicate a linkage between immunoregulation by T cells and spontaneous osteoclasts formation with increased levels of tumor necrosis factors-α, receptor activator of nuclear factor kappa-B ligand and inteleukin-7 production. In the light of these results, it would be of crucial importance to deepen the correlation between systemic bone remodeling diseases and spontaneous osteoclastogenesis as well as to investigate in detail the mechanisms underlying this phenomenon and the clinical relevance in bone remodeling disease diagnosis and monitoring.

Collagen type I coating stimulates bone regeneration and osteointegration of titanium implants in the osteopenic rat.

PURPOSE: To investigate the effects of titanium implants functionalised with collagen type I (TiColl) on bone regeneration and osteointegration in a healthy and osteopenic rat animal model. METHOD: TiColl screws were implanted into the femoral condyles of healthy and osteopenic rats and compared with acid-etched titanium (Ti) screws. The osteointegration process was evaluated by a complementary approach combining microtomographic, histological, histomorphometric and biomechanical investigations at four and 12 weeks. RESULTS: The TiColl screw also ensured a greater mechanical stability; the push-out values for TiColl screws increased from four to 12 weeks (+28 %). The energy necessary to detach the bone from the screw was significantly higher for TiColl-functionalised screws in comparison to Ti screws (+23 %) at 12 weeks. Histomorphometric investigation revealed that total bone-to-implant contact was higher in TiColl screws in comparison to Ti screws (P < 0.05) and at epiphyseal level, increased bone-to-implant contact was found with TiColl screws in comparison to Ti screws (P < 0.05) in an ovariectomy (OVX) condition. A significant increase in the measured total bone ingrowth from four to 12 weeks was detected for both materials, but more significant for the TiColl material (P < 0.0005). Finally, bone ingrowth in the TiColl group was significantly higher (P < 0.005) in comparison to that of Ti screws in the SHAM condition at metaphyseal level at 12 weeks. CONCLUSION: The present results showed that TiColl is effective in promoting implant osteointegration even in compromised bone.

Adipose-derived mesenchymal stem cells for cartilage tissue engineering: state-of-the-art in in vivo studies.

Several therapeutic approaches have been developed to address hyaline cartilage regeneration, but to date, there is no universal procedure to promote the restoration of mechanical and functional properties of native cartilage, which is one of the most important challenges in orthopedic surgery. For cartilage tissue engineering, adult mesenchymal stem cells (MSCs) are considered as an alternative cell source to chondrocytes. Since little is known about adipose-derived mesenchymal stem cell (ADSC) cartilage regeneration potential, the aim of this review was to give an overview of in vivo studies about the chondrogenic potential and regeneration ability of culture-expanded ADSCs when implanted in heterotopic sites or in osteoarthritic and osteochondral defects. The review compares the different studies in terms of number of implanted cells and animals, cell harvesting sites, in vitro expansion and chondrogenic induction conditions, length of experimental time, defect dimensions, used scaffolds and post-explant analyses of the cartilage regeneration. Despite variability of the in vivo protocols, it seems that good cartilage formation and regeneration were obtained with chondrogenically predifferentiated ADSCs (1 × 10(7) cells for heterotopic cartilage formation and 1 × 10(6) cells/scaffold for cartilage defect regeneration) and polymeric scaffolds, even if many other aspects need to be clarified in future studies.

Histological, histomorphometric and microtomographic analyses of retrieval hip resurfacing arthroplasty failed at different times.

BACKGROUND: Metal-on-metal hip resurfacing arthroplasty (HR) has been gaining popularity especially for young and active patients. Although different series report good mid-term results, the long-term outcome and failure mechanisms are still concerning. In this consecutive revision case series, 9 retrieved specimens of a failed Birmingham Hip Resurfacing (BHR) were divided according to the time to fracture: 3 specimens failed at less than 6 months (Group 1), 3 failed between 6 months and 3 years (Group 2) and 3 failed later than 3 years (Group 3). The objective of the study was to examine by a specific quantitative histomorphometry and microtomography (micro-CT) method the characteristics of bone quality and its microarchitecture in retrieved metal-on-metal HR. METHODS: A series of 948 BHR were performed between 2001 and 2009. Among these implants 10 failures occurred and nine of these underwent revision surgery and were examined by histomorphometry and micro-CT. RESULTS: Histomorphometry showed a significant increase in trabecular separation (Tb.Sp) in Group 3 in comparison with Group 1 (113%, p < 0.05). In the top region, micro-CT showed that Groups 2 and 3 presented significant lower bone volume (Group 2: 61%, p < 0.005; Group 3: 1%, p < 0.05), trabecular number (Group 2: 53%, p < 0.005; Group 3: 40%, p < 0.05), and higher Tb.Sp (Group: 71%,p < 0.05) when compared to Group 1. Additionally, histomorphometry showed that the top regions in Group 1 had a significantly lower mean percentage of empty osteocyte lacunae than the top regions in both Group 2 and 3 (p < 0.05). CONCLUSIONS: This study showed that the morphometric parameters considered are crucial for a good understanding of mechanical properties of HR and may be of significant importance in the pathogenesis of HR failure particularly in the development of late fractures.

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.

Preliminary 2-year report on treatment outcomes for 6-mm-long implants in posterior atrophic mandibles.

PURPOSE: The aim of this study was to prospectively evaluate clinical and radiographic outcomes of ultrashort implants (4-mm diameter, 6-mm length) supporting fixed partial dentures in severely atrophic posterior mandibles. MATERIALS AND METHODS: Twenty-five patients with posterior edentulous mandibular spans and 7- to 8-mm residual bone heights above the mandibular canal were enrolled. In total, 61 submerged implants were placed and loaded 5 to 6 months later. Patients were followed for 2 years after prosthesis connection with clinical, radiographic, and resonance frequency analysis (RFA) examinations. RESULTS: Two implants failed in one patient before loading; all other implants showed favorable clinical and radiographic findings throughout the observation period (2-year survival and success rate: 96.8%). Postoperative pain and swelling were negligible. Mean changes in marginal bone levels were stable (0.40 ± 0.23, 0.51 ± 0.38, and 0.60 ± 0.13 mm after 6 months and 1 and 2 years, respectively) and were unaffected by measured crown-to-implant ratios (range: 1.31 to 3.12). Mean RFA values increased significantly from implant placement (67.35 ± 6.67) to 2 years (72.91 ± 5.07, P < .0001). Prosthetic complications included two prosthesis decementations, three ceramic veneer chippings, and one prosthesis screw loosening. CONCLUSION: Within the limitations of the short follow-up period, the use of 6-mm-long implants was a predictable treatment method for patients with atrophic posterior mandibles and increased crown-to-implant ratios.

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.

Pietro Loreta and his contribution to surgery in the 19th century.

Pietro Loreta (1831 to 1889), head of surgery at the University of Bologna, Italy, is at present a little-known name. However, in the field of surgery in the second half of the 19th century, his contributions to various areas, especially that of bladder stone treatment and gastric surgery, aroused great interest also at the international level. This survey focuses on both of these subjects that are particularly indicative of Loreta's activity. While he was trying to improve the operation of perineal cystotomy, which was about to be abandoned, he was faced with the new frontier of gastrointestinal tract surgery. Surgery was in rapid transformation, and the practice of a general surgeon still encompassed the domains of different surgical specialties, which would develop individually afterward. Loreta was a pupil of the outstanding surgeon Francesco Rizzoli and some of his pupils such as Alessandro Codivilla and Bartolo Nigrisoli became heads of surgery. His attitude of caution, that he recommended in his writings, is more remarkable considering his problematic nature and might be the most significant and original trait of Loreta's personality.

Influence of implant-abutment interface design on bone and soft tissue levels around immediately placed and restored single-tooth implants: a randomized controlled clinical trial.

PURPOSE: The purpose of the present study was to compare the clinical and radiographic outcomes of single implants immediately placed and restored with two different implant-abutment connections. MATERIALS AND METHODS: Forty subjects requiring single maxillary premolar replacement were consecutively included in this study and prospectively followed for 12 months. One implant was placed at the time of tooth extraction and immediately restored in each patient. Subjects were randomly selected to receive either prosthetic abutments with a Morse taper connection and a platform switch (test group) or conventional abutments with an internal connection and a matching diameter (control group). A provisional screw-retained crown was positioned and adjusted for nonfunctional loading within 24 hours. Four months later, the definitive crowns were delivered. Periodontal parameters and clinical and radiographic measurements of soft and hard tissue levels were recorded at the moment of prosthesis placement and at 4 and 12 months afterward. Means of the two groups were compared using paired and independent-sample t tests (P = .05). RESULTS: Of the 40 patients recruited, 38 (24 women and 14 men) completed the study. No implants were lost in the control group, whereas one implant failed in the test group. At the 12-month examination, no statistically significant differences were seen between the two groups for periodontal parameters, marginal soft tissue level change, or papilla height (P > .05), but greater marginal bone loss was observed at the control sites (0.51 ± 0.24 mm) compared to the test sites (0.2 ± 0.17 mm) (P = .0004). CONCLUSION: Although the control group demonstrated a slight increase in marginal bone loss compared to the test group, the peri-implant soft tissues were very stable with both types of implant-abutment connection after 12 months of loading.

Osteogenic protein-1 associated with mesenchymal stem cells promote bone allograft integration.

Limited incorporation and modest bone remodeling can cause allograft failure. We investigated whether mesenchymal stem cells (MSCs) and osteogenic protein-1 (OP-1) can improve allograft integration. A 3-cm full-size intercalary bone defect was created in the mid-diaphysis of the metatarsal bone of the sheep and it was replaced with an allograft alone (control group), or with MSCs (MSC group), OP-1 (OP-1 group), or MSCs and OP-1 (MSC + OP-1 group). Radiographic results showed a faster and complete integration of the allograft in the MSC + OP-1 group. Histology demonstrated that the amount of new bone was significantly greater inside the graft and a longer vessel penetration in the MSC + OP-1 group than in others. Mechanical strength of the allograft was not compromised by the high rate of bone remodeling. These results demonstrated that the association of MSCs and OP-1 improve bone allograft integration promoting an almost complete bone restoring.

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.

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 occlusal loading of immediately placed implants supporting fixed restorations in completely edentulous arches: a 1-year prospective pilot study.

BACKGROUND: The aims of this pilot study were to evaluate the efficacy of treatment consisting of the immediate loading of implants placed immediately after tooth extraction in full-arch restorations and to compare the clinical and radiographic outcomes of implants placed in healed versus postextraction sites in the same group of patients. METHODS: Twenty-three patients who needed full-arch restorations were treated. One hundred forty-four implants were placed: 59 after tooth extraction (test group) and 85 in healed sites (control group). Within 48 to 72 hours of implant placement, nine maxillary and 15 mandibular arches received screw-retained fixed prostheses, consisting of a titanium framework fabricated with a computer-aided design and manufacturing techniques and composite resin teeth. The insertion torque for implants was >or=30 Ncm. Implant stability measurements (ISQ) and radiographs of the marginal bone level (MBL) change were performed at prosthesis delivery and after 1 year. RESULTS: One implant in the test group and one implant in the control group failed, giving a cumulative success rate of 98.6%; the prosthesis survival rate was 100%. At the 1-year follow-up, no statistically significant difference was found between the control and test sites with respect to MBL change (0.47 +/- 0.18 mm versus 0.57 +/- 0.27 mm) or mean ISQ values (62.24 +/- 1.92 versus 61.34 +/- 2.15). CONCLUSION: These preliminary data suggest that immediate loading of implants placed immediately after extraction may be a viable treatment option for edentulous arches when implants are stable at insertion and are rigidly splinted with screw-retained titanium-resin prostheses.

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.

Alveolar ridge augmentation with titanium mesh and a combination of autogenous bone and anorganic bovine bone: a 2-year prospective study.

BACKGROUND: Recently, the use of bovine bone mineral (BBM) in combination with autogenous bone for alveolar ridge augmentation before implant placement has increased in favor because of concerns over morbidity associated with extraoral donor sites. The aim of this prospective study was to evaluate the clinical and radiographic parameters of implants placed in augmented ridges using a 70:30 mixture of autogenous bone and BBM in association with micro-mesh over a 2-year period. METHODS: Sixteen partially edentulous patients requiring bone augmentation were consecutively treated for 19 reconstructive procedures and delayed implant placement (44 implants) after 8 to 9 months of submerged mesh healing. Clinical examinations were performed and radiographs of the implants were taken 6 months after prosthetic loading and once a year during a 2-year follow-up. RESULTS: Only one (5.3%) of the 19 micro-meshes became exposed after 2 months and was removed. Computed tomography scans of the alveolar ridge pre- and postreconstruction demonstrated mean vertical augmentation of 3.71 +/- 1.24 mm and mean horizontal augmentation of 4.16 +/- 0.59 mm. All of the implants were retained after 2 years, yielding a 100% survival rate. The mean bone resorption around the implants was 1.37 +/- 0.32 mm during the observation period. Only three implants demonstrated bone resorption >2 mm, whereas 41 implants were considered clinically successful, resulting in a success rate of 93.1%. CONCLUSION: This 2-year prospective study demonstrated that implants placed into augmented bone using this technique exhibited peri-implant stability with high survival (100%) and success (93.1%) rates.

Xenograft versus extraction alone for ridge preservation after tooth removal: a clinical and histomorphometric study.

BACKGROUND: The preservation of bone volume immediately after tooth removal might be necessary to optimize the success of implant placement in terms of esthetics and function. The objectives of this randomized clinical trial were two-fold: 1) to compare the bone dimensional changes following tooth extraction with extraction plus ridge preservation using corticocancellous porcine bone and a collagen membrane; and 2) to analyze and compare histologic and histomorphometric aspects of the extraction-alone sites to the grafted sites. METHODS: Forty subjects who required tooth extraction and implant placement were enrolled in this study. Using a computer-generated randomization list, the subjects were randomly assigned to the control group (EXT; extraction alone) or to the test group (RP; ridge-preservation procedure with corticocancellous porcine bone and collagen membrane). The following parameters were assessed immediately after extraction and 7 months prior to implant placement: plaque index, gingival index, bleeding on probing, horizontal ridge width, and vertical ridge changes. A bone biopsy was taken from the control and test sites 7 months after the surgical treatment. Histologic and histomorphometric analyses were also performed. RESULTS: A significantly greater horizontal reabsorption was observed at EXT sites (4.3+/-0.8 mm) compared to RP sites (2.5+/-1.2 mm). The ridge height reduction at the buccal side was 3.6+/-1.5 mm for the extraction-alone group, whereas it was 0.7+/-1.4 mm for the ridge-preservation group. Moreover, the vertical change at the lingual sites was 0.4 mm in the ridge-preservation group and 3 mm in the extraction-alone group. Forty biopsies were harvested from the experimental sites (test and control sites). The biopsies harvested from the grafted sites revealed the presence of trabecular bone, which was highly mineralized and well structured. Particles of the grafted material could be identified in all samples. The bone formed in the control sites was also well structured with a minor percentage of mineralized bone. The amount of connective tissue was significantly higher in the extraction-alone group than in the ridge-preservation group. CONCLUSIONS: The ridge-preservation approach using porcine bone in combination with collagen membrane significantly limited the resorption of hard tissue ridge after tooth extraction compared to extraction alone. Furthermore, the histologic analysis showed a significantly higher percentage of trabecular bone and total mineralized tissue in ridge-preservation sites compared to extraction-alone sites 7 months after tooth removal.