Identification of a Sjögren's syndrome susceptibility locus at OAS1 that influences isoform switching, protein expression, and responsiveness to type I interferons.

Sjögren's syndrome (SS) is a common, autoimmune exocrinopathy distinguished by keratoconjunctivitis sicca and xerostomia. Patients frequently develop serious complications including lymphoma, pulmonary dysfunction, neuropathy, vasculitis, and debilitating fatigue. Dysregulation of type I interferon (IFN) pathway is a prominent feature of SS and is correlated with increased autoantibody titers and disease severity. To identify genetic determinants of IFN pathway dysregulation in SS, we performed cis-expression quantitative trait locus (eQTL) analyses focusing on differentially expressed type I IFN-inducible transcripts identified through a transcriptome profiling study. Multiple cis-eQTLs were associated with transcript levels of 2'-5'-oligoadenylate synthetase 1 (OAS1) peaking at rs10774671 (PeQTL = 6.05 × 10-14). Association of rs10774671 with SS susceptibility was identified and confirmed through meta-analysis of two independent cohorts (Pmeta = 2.59 × 10-9; odds ratio = 0.75; 95% confidence interval = 0.66-0.86). The risk allele of rs10774671 shifts splicing of OAS1 from production of the p46 isoform to multiple alternative transcripts, including p42, p48, and p44. We found that the isoforms were differentially expressed within each genotype in controls and patients with and without autoantibodies. Furthermore, our results showed that the three alternatively spliced isoforms lacked translational response to type I IFN stimulation. The p48 and p44 isoforms also had impaired protein expression governed by the 3' end of the transcripts. The SS risk allele of rs10774671 has been shown by others to be associated with reduced OAS1 enzymatic activity and ability to clear viral infections, as well as reduced responsiveness to IFN treatment. Our results establish OAS1 as a risk locus for SS and support a potential role for defective viral clearance due to altered IFN response as a genetic pathophysiological basis of this complex autoimmune disease.

Beta-tricalcium phosphate/type I collagen cones with or without a barrier membrane in human extraction socket healing: clinical, histologic, histomorphometric, and immunohistochemical evaluation.

The aim of this study was to investigate the healing of human extraction sockets filled with ß-tricalcium phosphate and type I collagen (ß-TCP/Clg) cones with or without a barrier membrane. Twenty patients were divided in two groups: (A) ß-TCP/Clg non-membrane and (B) ß-TCP/Clg + barrier membrane. Clinical examination and biopsies from the grafted sites were collected 9 months later. Bone samples were analyzed using histomorphometry and immunohistochemistry. The horizontal dimension of the alveolar ridge was significantly reduced 9 months after socket preservation in the non-membrane group. There was bone formation with no significant differences between the two groups in the areas occupied by new bone (A = 42.4%; B = 45.3%), marrow (A = 42.7%; B = 35.7%), or residual graft (A = 9.7%; B = 12.5%). Immunohistochemistry revealed osteonectin expression in both groups. Both groups demonstrated sufficient amounts of vital bone and socket morphology to support dental implant placement after the 9-month healing period. A future trial to evaluate the alveolar outcomes at an earlier 6-month time point rather than the 9 months used in this study would be of interest.

Monocytes: super cells for bone regeneration.

Monocytes are progenitor cells that lead the inflammatory cascade reaction responsible for guiding revascularization and regeneration of tissue at injury sites. They do this by secreting inductive cytokines responsible for endothelial cell migration. When released into the peripheral blood, monocytes enter tissues and become macrophages. Monocytes also trigger the body's defense mechanism against microbial invasion by lysing and removing cell debris and dead tissue. The aim of this article is to explain the role of monocytes in the processes of bone healing and regeneration and describe their interaction with stem cells and other entities. Results of a pilot histomorphometric study in which concentrated monocytes were combined with demineralized allograft material to augment implant-placement sites in 2 patients also are presented.

Theoretical model for bone graft success.

Theoretical assumptions must correlate with clinical efficacy and good surgical outcomes to be of value to clinicians and patients. This article examines several common assumptions regarding the use of bone marrow aspirate to enhance bone grafting procedures. Contrary to these assumptions, evidence-based research suggests the following: (1) No more than 4 mL of bone marrow should be aspirated from a single donor site. Aspiration of more than that amount does not substantially increase the number of progenitor cells harvested but instead dilutes the concentration of progenitor cells with other nucleated cells from peripheral blood. (2) Bone marrow aspirate should not be concentrated using centrifuge technology. Rather than isolating desired cells, centrifuging concentrates all nucleated cells, increasing the overall metabolic activity to the detriment of the desired cells. (3) Increasing the volume of graft material brought to a graft site has the unwanted effect of increasing the diffusion distance for oxygen and nutrients and may lead to graft necrosis. (4) Histomorphometric analysis is the most effective method of evaluating bone graft outcomes because only such analysis allows for quantification of the percentage of bone and viable cells within a bone core biopsy.

Antral membrane elevation using a post graft: a crestal approach.

The crestal approach to elevating the antral membrane by a resorbable StemVie post is a modification of the sinus lift technique. This technique can add 4-10 mm of bone height for severely atrophic ridges in areas that are difficult to access through a lateral window. The procedure is minimally invasive, simple, and predictable, and has less postoperative morbidity due to smaller flap design and minimal osteotomy. If sufficient alveolar bone is present for stabilization, an implant can be placed simultaneously with an antral elevation and graft. The StemVie post resorbs completely and is replaced by the patient's own bone. Healing is enhanced with the addition of bone marrow aspirate and/or peripheral venous blood to the StemVie post graft. The graft will absorb the blood or the marrow, allowing them to infiltrate through the porosity present in the graft. Bone marrow aspirate aids in healing with the addition of precursor osteoblastic stem cells, cytokines, and growth factors, while peripheral blood supplies mostly cytokines and growth factors.

Enhancing extraction socket therapy with a biphasic calcium sulfate.

Studies have shown that tooth extraction results in loss of bone volume, which compromises dental implant placement. Prevention of site collapse at the time of extraction is recommended. In this 4-month case series, 40 patients were treated with an innovative biphasic calcium sulfate graft, demonstrating its ability to preserve or augment socket volume and resorb in the time period desired between extraction and implant placement. Some representative samples were retrieved at the time of implant placement and evaluated histologically and morphometrically for vital bone formation.

The crestal approach: antral membrane elevation via a post graft.

The crestal approach to elevating the antral membrane by a resorbable StemVie Post is a modification of the sinus lift technique. This technique can add 4 to 10 mm bone height for severely atrophic ridges in areas that are difficult to access through a lateral window. The procedure is minimally invasive, simple, predictable, and has less postoperative morbidity because of smaller flap design and minimal osteotomy. If sufficient alveolar bone is present for stabilization, an implant can be placed simultaneous with antral elevation and graft. The StemVie Post completely resorbs and is replaced by the patient's own bone.

The correlation of bone mineral density and histologic data in the early grafted maxillary sinus: a preliminary report.

PURPOSE: : Implant success in the grafted maxillary sinus is dependent on the formation of new vital autogenous bone and its mineral density. Different bone graft materials and graft combinations have been used in the sinus augmentation procedure to support dental implants under occlusal loads. The goal of this study was to determine whether it is possible to observe a direct correlation between bone mineral density and histologic data in the grafted maxillary sinus. Based on the observed histological findings, we propose a bone mineral density classification that has 3 rather than 4 types of bone. MATERIALS AND METHODS: : A total of 15 patients participated in this study, all of which had only 1 sinus grafted. A total of 34 dental implants were placed in the grafted sinuses. In 7 patients, designated as group A, a 50:50 composite ratio of autogenous and allogeneic bone was used to graft the sinuses. Four patients had the sinuses grafted with a 50:50 composite ratio of a naturally occurring marine algae hydroxyapatite graft material and autogenous bone. One patient had the sinus grafted with 100% autogenous bone. In this group of patients, a total of 25 dental implants were surgically placed 14 to 20 weeks after sinus grafting. The implants were restored 12 weeks later. No implant failures were observed over a 52-week period. The last 3 patients, designated as group B, completed implant surgery beyond the 52-week end point of the study for various reasons. They provided a unique opportunity to histologically observe bone maturation at 68, 88, and 260 weeks, respectively. Using cone beam computed tomography (CT) technology and 3D-CT interactive software, bone mineral density in Hounsfield unit values were recorded during different healing time periods. RESULTS: : In all 15 patients, bone mineral density was observed to steadily increase during the 52-week observation period and beyond, as evidenced by the increase in Hounsfield unit values and the formation of new, vital autogenous trabecular bone. CONCLUSION: : Histologic and histomorphometric data demonstrate a definite correlation with the formation of new, vital autogenous trabecular bone and bone mineral density (quality) that permits early loading of implants in the grafted maxillary sinus.

Simultaneous versus two-stage implant placement and guided bone regeneration in the canine: histomorphometry at 8 and 16 months.

AIM: To compare the effect of timing of implant placement and guided bone regeneration (GBR) procedure on osseointegration and newly formed bone at 8 and 16 months. MATERIAL AND METHODS: In seven dogs, four different sites were bilaterally established: (1) an implant placed in a 6-month healed (6m-GBR) bovine bone mineral (BBM) grafted site; (2) a simultaneously placed implant with the grafted BBM (Si-GBR) followed by a membrane coverage; (3) an implant placed in a membrane-protected non-grafted defect; and (4) an implant placement in a naturally healed site (Cont). Histomorphometry was obtained at 8 and 16 months post-implant placement. Bone-implant contact (BIC), crestal bone resorption (CBR), vertical intra-bony (VIB) defect, bone (BAF) and particle (PAF) area fractions, and osteoconductivity (CON) levels were measured. RESULTS: In all sites, BIC ranged between 62% and 79% with no significant differences. PAF ranged from 17% to 27%, with no effect of time. At 8 and 16 months, BAF was significantly smaller at the Si-GBR site when compared with all other sites, CON was significantly greater at the 6m-GBR site, and CBR and VIB were significantly smaller at the 6m-GBR when compared with the Si-GBR sites. CONCLUSIONS: The simultaneous and delayed techniques both showed a similar osseointegration level over time. However, the staged approach showed enhanced newly formed bone, higher osteoconduction around the grafted mineral, less CBR, and smaller vertical bone defect over time compared with the combined approach.

Alveolar ridge augmentation using implants coated with recombinant human growth/differentiation factor-5: histologic observations.

OBJECTIVES: In vitro and in vivo preclinical studies suggest that growth/differentiation factor-5 (GDF-5) may induce local bone formation. The objective of this study was to evaluate the potential of recombinant human GDF-5 (rhGDF-5) coated onto an oral implant with a purpose-designed titanium porous oxide surface to stimulate local bone formation including osseointegration and vertical augmentation of the alveolar ridge. MATERIALS AND METHODS: Bilateral, critical-size, 5 mm, supraalveolar peri-implant defects were created in 12 young adult Hound Labrador mongrel dogs. Six animals received implants coated with 30 or 60 microg rhGDF-5, and six animals received implants coated with 120 microg rhGDF-5 or left uncoated (control). Treatments were alternated between jaw quadrants. The mucoperiosteal flaps were advanced, adapted, and sutured to submerge the implants for primary intention healing. The animals received fluorescent bone markers at weeks 3, 4, 7, and 8 post-surgery when they were euthanized for histologic evaluation. RESULTS: The clinical examination showed no noteworthy differences between implants coated with rhGDF-5. The cover screw and implant body were visible/palpable through the alveolar mucosa for both rhGDF-5-coated and control implants. There was a small increase in induced bone height for implants coated with rhGDF-5 compared with the control, induced bone height averaging (+/-SD) 1.6+/-0.6 mm for implants coated with 120 microg rhGDF-5 versus 1.2+/-0.5, 1.2+/-0.6, and 0.6+/-0.2 mm for implants coated with 60 microg rhGDF-5, 30 microg rhGDF-5, or left uncoated, respectively (p<0.05). Bone formation was predominant at the lingual aspect of the implants. Narrow yellow and orange fluorescent markers throughout the newly formed bone indicate relatively slow new bone formation within 3-4 weeks. Implants coated with rhGDF-5 displayed limited peri-implant bone remodelling in the resident bone; the 120 microg dose exhibiting more advanced remodelling than the 60 and 30 microg doses. All treatment groups exhibited clinically relevant osseointegration. CONCLUSIONS: rhGDF-5-coated oral implants display a dose-dependent osteoinductive and/or osteoconductive effect, bone formation apparently benefiting from local factors. Application of rhGDF-5 appears to be safe as it is associated with limited, if any, adverse effects.

Alveolar ridge augmentation using implants coated with recombinant human bone morphogenetic protein-7 (rhBMP-7/rhOP-1): histological observations.

BACKGROUND: Pre-clinical studies have shown that recombinant human bone morphogenetic protein-2 (rhBMP-2) coated onto purpose-designed titanium porous-oxide surface implants induces clinically relevant bone formation and osseointegration. The objective of this study was to examine the potential of rhBMP-7, also known as recombinant human osteogenic protein-1 (rhOP-1), coated onto titanium porous-oxide surface implants to support vertical alveolar ridge augmentation and implant osseointegration. MATERIALS AND METHODS: Bilateral, critical-size, 5 mm, supraalveolar peri-implant defects were created in six young adult Hound Labrador mongrel dogs. The animals received implants coated with rhBMP-7 at 1.5 or 3.0 mg/ml randomized to contra-lateral jaw quadrants. The mucoperiosteal flaps were advanced, adapted, and sutured to submerge the implants for primary intention healing. The animals received fluorescent bone markers at 3, 4, 7, and 8 weeks post-surgery when they were euthanized for histological evaluation. RESULTS: Without striking differences between treatments, the implant sites exhibited a swelling that gradually regressed to become hard to palpation disguising the implant contours. The histological evaluation showed robust bone formation; the newly formed bone assuming characteristics of the contiguous resident bone, bone formation (height and area) averaging 4.1+/-1.0 versus 3.6+/-1.7 mm and 3.6+/-1.9 versus 3.1+/-1.8 mm(2); and bone density 56%versus 50% for implants coated with rhBMP-7 at 1.5 and 3.0 mg/ml, respectively. Both treatments exhibited clinically relevant osseointegration, the corresponding bone-implant contact values averaging 51% and 47%. Notable peri-implant resident bone remodelling was observed for implants coated with rhBMP-7 at 3.0 mg/ml. CONCLUSIONS: rhBMP-7 coated onto titanium porous-oxide surface implants induces clinically relevant local bone formation including osseointegration and vertical augmentation of the alveolar ridge, the higher concentration/dose associated with some local side effects.

Evaluation of implants coated with rhBMP-2 using two different coating strategies: a critical-size supraalveolar peri-implant defect study in dogs.

BACKGROUND: Implants coated with recombinant human bone morphogenetic protein-2 (rhBMP-2) induce relevant bone formation but also resident bone remodelling. OBJECTIVES: To compare the effect of implants fully or partially coated with rhBMP-2 on new bone formation and resident bone remodelling. MATERIALS AND METHODS: Twelve, male, adult, Hound Labrador mongrel dogs were used. Critical-size, supraalveolar, peri-implant defects received titanium porous oxide surface implants coated in their most coronal aspect with rhBMP-2 (coronal-load/six animals) or by immersion of the entire implant in an rhBMP-2 solution (soak-load/six animals) for a total of 30 mug rhBMP-2/implant. All implants were air-dried. The animals were euthanized at 8 weeks for histometric evaluation. RESULTS: Clinical healing was uneventful. Supraalveolar bone formation was not significantly affected by the rhBMP-2 application protocol. New bone height and area averaged (+/- SE) 3.4 +/- 0.2 versus 3.5 +/- 0.4 mm and 2.6 +/- 0.4 versus 2.5 +/- 0.7 mm(2) for coronal-load and soak-load implants, respectively (p>0.05). The corresponding bone density and bone-implant contact (BIC) recordings averaged 38.0 +/- 3.8%versus 34.4 +/- 5.6% and 25.0 +/- 3.8%versus 31.2 +/- 3.3% (p>0.05). In contrast, resident bone remodelling was significantly influenced by the rhBMP-2 application protocol. Bone density outside the implants threads averaged 74.7 +/- 3.8% and 50.8 +/- 4.1% for coronal-load and soak-load implants, respectively (p<0.05); bone density within the thread area averaged 51.8 +/- 1.2% and 37.8 +/- 2.9%, and BIC 70.1 +/- 6.7% and 43.3 +/- 3.9% (p<0.05). CONCLUSION: Local application of rhBMP-2 appears to be a viable technology to support local bone formation and osseointegration. Coronal-load implants obviate resident bone remodelling without compromising new bone formation.

Screw "tent-pole" grafting technique for reconstruction of large vertical alveolar ridge defects using human mineralized allograft for implant site preparation.

PURPOSE: The purpose of this study was to evaluate the effectiveness of using titanium screws in combination with particulate human mineralized allograft, in a "tenting" fashion, to augment large vertical alveolar ridge defects for implant placement. MATERIALS AND METHODS: This prospective case study evaluated augmentation in consecutive patients with large (>7 mm) vertical alveolar ridge defects. Vertical ridge augmentation was performed using mineralized allograft placed around titanium screws to tent out the soft tissue matrix. The ridges were clinically evaluated 4 to 5 months after augmentation, and implants were placed at that time. Bone cores were harvested from all patients for histologic evaluations. RESULTS: Fifteen patients were treated in this prospective case study, and the mean vertical augmentation was 9.7 mm. Two patients had wound dehiscence resulting in loss of graft and requiring secondary grafting before implant placement. Five patients required 2-stage grafting procedures to achieve ideal ridge height before implant placement. Clinical evaluation of the grafted sites upon re-entry revealed uniform ridge anatomy. Histomorphometric analysis of 7 specimens revealed a mean bone content of 43%. A total of 32 implants were placed into grafted sites in 15 patients. All implants were integrated and successfully restored. Mean follow-up was 16.8 months after implant placement. CONCLUSIONS: Tenting of the periosteum and soft tissue matrix with titanium screws maintains space and minimizes resorption of mineralized particulate allograft. This technique offers predictable functional and esthetic reconstruction of large vertical defects without the use of autogenous bone and is capable of osseointegration. More studies are needed to evaluate the stability of vertically grafted bone after long-term loading.

Histologic evaluation of recombinant human platelet-derived growth factor-BB after use in extraction socket defects: a case series.

Recent advancements in the arena of therapeutic molecular enhancement have shown favorable clinical findings for periodontics. However, further studies to optimize clinical outcomes using this technology are warranted. Twelve premolar extraction sockets were assigned randomly for treatment with 0.3 mg/mL recombinant human platelet-derived growth factor (rhPDGF-BB) combined with either a collagen containing anorganic deproteinized bovine bone (xenograft) or beta-tricalcium phosphate (b-TCP). Histologic evaluation of extraction socket healing was performed at 3 months. Histologic findings were similar with b-TCP and the xenograft, having 21% and 24% vital bone, respectively. The use of rhPDGF-BB with either b-TCP or a xenograft resulted in uneventful socket healing. At reentry, all implants were placed without the need for further grafting, and 100% implant success was recorded at the time of final evaluation (restoration completion).

Bone grafting by means of a tunnel dissection: predictable results using stem cells and matrix.

Bone marrow aspirate has been shown to add stem cells, growth factors, and cytokines to bone graft matrices used in bone augmentation sites. The combination of bone marrow aspirate and resorbable scaffold material has a significant osteogenic capability that exceeds that of autogenous bone grafts. This article describes a subperiosteal tunneling technique for applying such grafts to defective sites. Treatment of 2 patients for whom the technique was used to graft 6 deficient sites is described. Histological results and histomorphometric analysis of bone core samples taken from 4 of the 6 grafting sites are also reported. Analysis of the 4 bone cores taken between 4 and 6 months showed a range of 34% to 45% of new bone.

Cementum, pulp, periodontal ligament, and bone response after direct injury with orthodontic anchorage screws: a histomorphologic study in an animal model.

PURPOSE: To assess the histologic response of the periodontium, cementum, and pulp after intentional root injury with titanium screws. MATERIALS AND METHODS: Three female beagle dogs were used, and a total of 60 self-drilling/self-tapping miniscrews were manually inserted into the maxilla and the mandible with the intention of placement in close proximity or in direct contact with the roots. Digital radiographs were taken to select the sites with root injuries. After a 3-month period, the animals were killed and serial nondecalcified histologic sections were obtained with the miniscrew in place. RESULTS: Sixteen sites with significant root injury were identified. Four sites presented with cementum abrasion, 7 sites had dentin penetration up to 50% of the diameter of the screw, and 5 sites had miniscrew penetration into the pulp space with root fragmentation. At all damaged sites, continuous cementum repair could be observed. There was no evidence of external resorption or pulpal necrosis and/or inflammatory infiltrate. Point ankylosis was seen only in cases of severe injury with root fragmentation. Finally, woven bone was present along the miniscrew threads. CONCLUSION: When titanium screws penetrate root cementum or dentin, pulpal necrosis and/or inflammation was not observed at 12 weeks in an animal model. Cementum regenerates at every injury site, but ankylosis can occur with root fragmentation. Woven bone is present at the screw-bone interface even with root contact suggesting osteointegration.

Bone regeneration with autologous biomaterial; rapid induction of vital new bone in maxillary sinus floor by platelet concentrate alone at 23x baseline (PRP23x): a case report.

To date, most clinicians and researchers have been using platelet concentrate within the range of 4x to 8x baseline. In this case report a new procedure involving strategic pooling and triple spin was developed and used to concentrate platelets to 23x baseline. The concentrate alone was infused into morselized resorbable collagen sponge, activated with calcium chloride and autologous thrombin, then placed as an autologous graft into the left sinus floor of a healthy 80-year-old woman. The floor of the sinus had approximately 2 mm of bony height. A computed tomography scan taken after 5 months showed that new bone was formed and it was as dense as native bone around the surgical site. From the computed tomography scan bone density analysis using Hounsfield Units revealed that the bone formed was D3 bone (518.3 +/- 224.9 Hounsfield Units) and it was as dense as native bone on the axial, coronal and sagittal slices. Histomorphometric analysis of 2 bone core biopsies taken after 6 months showed that 1 core had 34% bone of which 98% was vital new bone and the other core had 39% bone of which 100% was vital new bone. The height of the bone formed in the sinus floor was 12 mm. It was also characterized by good trabecular pattern and connectivity. The quality of the bone generated was such that 2 endosseous implants were placed and torqued to 30 N cm after the cores were removed.

Root and pulp response after intentional injury from miniscrew placement.

INTRODUCTION: The purpose of this study was to evaluate the effects on the pulp and supporting tissues when miniscrews severely abrade the root surface. METHODS: Sixty self-drilling and self-tapping miniscrews were placed between the premolars and molars of 3 beagles (20 miniscrews per dog). The miniscrews were placed according to the protocol suggested by the manufacturer, but with the intention of inflicting root damage. Radiographs were taken of all 60 interdental alveolar sites, 5 in each quadrant, and sites that evidenced root proximity were identified. The animals were killed at 12 weeks, and 20 of the most probable injury sites were selected for histologic analysis. Serial nondecalcified sections and microcomputed tomography scans were obtained with the implants in place. RESULTS: There was no histologic evidence of inflammatory response either at the root surface or in the pulp. Pulp necrosis, external resorption, and ankylosis were not found, but reparative cementum was seen at each injury site. The presence of woven bone along miniscrew threads lends evidence to support the osseointegration of miniscrews. CONCLUSIONS: Permanent damage to the pulp and supporting tissues is not a regular occurrence when miniscrews abrade or even enter the root surface.

Sinus grafting with a natural fluorohydroxyapatite for immediate load: a study with histologic analysis and histomorphometry.

The goal of this retrospective study was to evaluate the survival rates of dental implants placed in sinuses grafted with a 50:50 composite ratio of autogenous bone and a natural flourohydroxyapatite (FHA) combined with platelet-rich plasma (PRP) using an immediate-load protocol. The authors hypothesized that a 50:50 composite ratio of FHA and autogenous bone combined with PRP would permit immediate loading without compromising implant survival rates. Eleven patients with bilateral partial edentulism of the posterior maxilla were enrolled in this retrospective study. Autogenous bone used in the graft procedure was harvested from the tibia of the left lower extremity. Each patient was grafted with a 50:50 composite ratio of autogenous bone and FHA. Membranes were not used to cover the lateral wall osteotomy site. Platelet-rich plasma was added to the graft material to accelerate and enhance bone regeneration. Four to 6 months after the grafting procedure, 37 hydroxyapatite-coated dental implants were surgically placed and immediately loaded between 72 hours and 5 days later with custom titanium abutments and acrylic provisional restorations placed out of functional occlusion. Six months later, definitive ceramometal restorations were cemented on to the custom abutments. Patients were observed over a 52-week period. The overall implant survival rate was 97.3%. Histologic and histomorphometric analysis of core samples revealed formation of new vital bone in different graft specimens ranging from 23% to 34%. In each core bone sample, 100% of the bone sample was determined to be vital. In the grafted maxillary sinus, the natural FHA combined with autogenous bone in a 50:50 composite ratio with PRP is a suitable graft material permitting immediate load without compromising implant survival rates while decreasing the overall healing time.

Clinical evaluation alveolar ridge preservation with a beta-tricalcium phosphate socket graft.

PURPOSE: To determine the efficacy of an alloplastic graft material, consisting of a pure-phase beta-tricalcium phosphate (beta-TCP), in the preservation of ridge volume after tooth extraction and before dental implant placement. Histomorphometric analysis was completed on a few samples to determine the percentage of vital bone over a fixed healing period. MATERIALS AND METHODS: Patients requiring tooth extraction and bone regeneration before implant placement were included in this study. Measurements of alveolar width were made at the time of extraction and the time of implant placement. The extraction sites were grafted with a pure-phase beta-TCP and covered with a barrier. Approximately 6 months after surgery, the sites were reentered for implant placement. Cores were taken of the regenerated material for histologic analysis, with a trephine used as the first bur in preparation for some of the osteotomies. Implants were placed according to the manufacturers' recommendations and loaded at the appropriate time. RESULTS: The beta-TCP placed at the time of grafting extraction sockets was well tolerated in all sites with all of the barriers used. There were no incidences of postoperative infection or graft rejection. At the time of implant placement, much of the graft material had resorbed and been converted to vital alveolar bone. The implant recipient sites were dense and supported placement of endosseous dental implants that were fully stable. The width of the extraction sockets was preserved to 91% of the preoperative width. CONCLUSIONS: Extraction socket grafting with the pure-phase beta-TCP tested in this study and covered with either a resorbable collagen or dense polytetrafluoroethylene barrier is a predictable method for preserving alveolar dimensions. The graft material resorbs to a high percentage in the timeframe desired between extraction and dental implant placement, as shown clinically, radiographically, and histologically. In addition, the regenerated material in the socket has enough density to support implant placement with subsequent loading in the 4- to 6-month period used in this study.