Alveolar ridge regeneration in two-wall-damaged extraction sockets of an in vivo experimental model.

AIM: To determine the healing outcome following grafting with deproteinized porcine bone mineral (DPBM) with or without collagen membrane coverage in two-wall (both buccal and lingual)-damaged extraction sockets. MATERIALS AND METHODS: Distal roots of three mandibular premolars in six beagle dogs were extracted, and the whole buccal and lingual bony walls were surgically removed. Three treatment protocols were then applied according to the following group allocation: no graft (None), grafting DPBM (BG), and grafting DPBM with coverage by a collagen membrane (BG + M). Two observational periods (2 and 8 weeks) were used with the split-mouth design, and quantitative and qualitative analyses were performed by microcomputed tomography and histology. RESULTS: The dimensions of the alveolar ridge at both grafted sites (BG and BG + M) remained similar to those of the pristine ridge in the histologic and radiographic analyses, whereas the ungrafted sites (None) collapsed both vertically and horizontally. Both grafting protocols produced substantial bony regeneration, but the addition of a covering membrane enhanced the proportion of mineralized tissue within the augmented area, and the BG + M group also showed a significantly larger area of regenerated ridge than the None group (p < .05). CONCLUSIONS: Bone grafting with collagen membrane can maintain the alveolar ridge dimensions with substantial bone regeneration in a two-wall-damaged extraction socket.

Histologic analysis following grafting of damaged extraction sockets using deproteinized bovine or porcine bone mineral: A randomized clinical trial.

OBJECTIVES: This study histologically analyzed biopsy samples obtained from sites of damaged extraction socket grafting using deproteinized bovine bone mineral (DBBM) or deproteinized porcine bone mineral (DPBM) with coverage by a collagen membrane. MATERIAL AND METHODS: One hundred patients participated in this randomized controlled clinical trial of extraction socket grafts performed in cases of periodontally compromised teeth. All participants were blinded to their group allocations, and each material was grafted with coverage by collagen membranes after extraction of the tooth and removal of granulation tissue. At implant placement at 4 months, a biopsy was harvested at the implant site using a trephine was analyzed histologically. RESULTS: Eighty-five biopsy samples were acquired, of which 81 were finally included in the histologic analysis (42 in DBBM and 39 in DPBM group). Both DBBM and DPBM groups showed comparable proportions of residual biomaterial (12.37 ± 5.67% and 12.21 ± 5.75%, respectively), newly formed bone (15.07 ± 10.52% and 18.47 ± 11.47%, respectively), and nonmineralized tissue (72.56 ± 10.07% and 71.55 ± 15.47%, respectively). There were no significant differences in these histologic parameters between the two groups with different biomaterials. CONCLUSION: Comparable histologic bone formation was found in both socket grafted groups with DBBM or DPBM covered by collagen membranes in periodontally damaged extraction sockets. However, a wide variation in new bone formation was found after 4 months of postsurgical healing and a tendency of higher new bone formation was shown at damaged sockets that had an intact unilateral residual wall regardless of buccal or lingual side.

Clinical Factors and Cellular Responses of In Situ Human Alveolar Bone-Derived Mesenchymal Stromal Cells Associated With Early Periimplant Marginal Bone Loss: A Prospective Cohort Pilot Study.

PURPOSE: To investigate clinical factors and cellular responses of in situ human alveolar bone-derived mesenchymal stromal cells involved in early periimplant marginal bone loss. MATERIALS AND METHODS: Thirty-seven completely or partially edentulous patients were enrolled in this study. Periapical radiographs were taken at the time of implant surgery, at 3-month follow-up, and at 1-year follow-up. Univariate analysis and multiple logistic regression were performed to investigate the associations between marginal bone loss and study variables. The mRNA expression levels of 21 bone-remodeling- and tissue-healing-associated genes were analyzed by subgroup. RESULTS: Thirty-one patients with 98 implants were followed. The incidence and mean amount of bone loss were higher for overdentures than for other prosthesis and higher for the maxilla than for the mandible. The bone loss group showed lower mRNA expression levels of runt-related transcription factor-2, bone morphogenetic protein-2, and peroxisome proliferator-activated receptor gamma-2 and higher receptor activator of NKκB ligand/osteoprotegerin (RANKL/OPG) ratio. CONCLUSION: Within the limitations of the study, certain genes involved in bone remodeling (runt-related transcription factor-2 [Runx-2], bone morphogenetic protein-2 [BMP-2], and peroxisome proliferator-activated receptor gamma-2 [PPARγ-2]) and RANKL/OPG are correlated with early periimplant bone loss, with the type of suprastructure and the involved jaw being significant clinical factors.

Resonance Frequency Analysis of Tapered Implants Placed at Maxillary Posterior Sites After Lateral Sinus Augmentation: A 1.5-year Follow-Up Prospective Study.

OBJECTIVES: To use resonance frequency analysis to evaluate tapered implants placed at maxillary posterior sites after lateral sinus augmentation. MATERIALS AND METHODS: Patients who had missing teeth in the maxillary posterior area and required lateral sinus augmentation before implant placement were enrolled in this study. After a 6-month healing period, a tapered implant (Osstem TSIV) was placed. Implant success rate, survival rate, and marginal bone loss of the implants were measured. For resonance frequency analysis, implant stability quotient (ISQ) values were measured at each visit during a 1.5-year follow-up period. RESULTS: Twenty-four patients completed the study procedure. The residual bone height was 2.57 ± 1.10 mm (mean ± SD). Healing of the grafted area was uneventful in all cases, and 55 tapered implants were installed. The implant success rate was 95.56%, and the survival rate was 100% throughout the observation period. The marginal bone loss was limited to 0.22 ± 0.44 mm. ISQ increased gradually from 68.40 ± 11.14 to 82.24 ± 4.75 during the 1.5-year follow-up period. CONCLUSION: The tapered implants showed good initial and final stability after placement in the soft bone of the maxillary posterior area after lateral sinus augmentation.

Characteristics of Local Delivery Agents for Treating Peri-Implantitis on Dental Implant Surfaces: A Preclinical Study.

Local delivery agents (LDAs) are widely used in peri-implantitis treatments. The aim of this study was to identify LDAs remaining on the dental implant surfaces and to analyze the components of these residues after applying various cleaning methods. Implants were prepared with a sand-blasted, large-grit, acid-etched surface. Four kinds of LDAs were applied on the implant surfaces: chlorhexidine gel (group 2), tetracycline solution (group 3), and 2 kinds of minocycline hydrochloride agents (groups 4 and 5). Group 1 received normal saline as a control. Two cleaning methods were applied for different durations as follows: (1) running distilled water for 10 seconds (subgroup A), 5 minutes (subgroup B), and 15 minutes (subgroup C); and (2) water spray of a dental-unit chair for 10 seconds (subgroup D) and 5 minutes (subgroup E). Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to analyze the surface morphology and residue components for all implants. The amount of LDA removed from the implant surfaces in groups 1, 2, 3, and 5 increased with the cleaning duration and pressure. However, Minocline remained coated on the implant surfaces in group 4 under all cleaning conditions. Minocline could not be cleaned off well by water due to its hydrophobicity. Therefore, directly using this agent on implant surfaces with peri-implantitis should be carefully considered. The presence of LDA residues without drug efficacies on implant surfaces might interfere with reosseointegration and act as a reservoir of microorganisms.

Radiographic and histologic observations of sequential healing processes following ridge augmentation after tooth extraction in buccal-bone-deficient extraction sockets in beagle dogs.

OBJECTIVES: To evaluate dimensional ridge alterations and sequential healing processes following ridge augmentation after tooth extraction in damaged extraction sockets with buccal-bone-deficiency. MATERIAL AND METHODS: Bilateral dental roots of three mandibular premolars were extracted with entire removal of the buccal-bone plate in eight beagle dogs. Unilateral sites were grafted with biomaterials (test group) and contralateral sites were healed without grafting (control group). Observations were made after 1, 2, 4, and 8 weeks, and all sites were distributed evenly (n = 6 for each group and period). Radiographic/histomorphometric analyses were performed. RESULTS: In spontaneous healing of damaged extraction sockets, the dimension of regenerated alveolar ridge gradually increased until 4 weeks and then remained stable, but radiographic/histomorphometric analyses revealed evident dimensional shrinkage compared to the pristine tissue at 8 weeks in the coronal and middle areas. Bone grafting retained the pristine dimension of alveolar ridge, and newly formed bone area within the augmented space continuously expanded during the observational period to the outermost border of the space. CONCLUSIONS: Spontaneous healing of damaged extraction sockets caused substantial dimensional shrinkage. However, ridge augmentation can provide space into which new bone may grow continuously, resulting in the final dimensions comparable to those of the pristine alveolar ridge.

Chemokine in inflamed periodontal tissues activates healthy periodontal-ligament stem cell migration.

AIM: The present study aimed to characterize the expression pattern of chemokines obtained from inflamed periodontal defects and to determine the characteristics of human periodontal-ligament stem cells (hPDLSCs) migrated by each specific chemokine. MATERIALS AND METHODS: Both inflamed and healthy periodontal tissues were obtained from periodontitis patients (n = 11), and the chemokine expression levels were analyzed. The periodontal-tissue-specific chemokines were applied to healthy hPDLSCs from extracted teeth (n = 3), with FGF-2 acting as a positive control. Cells were separated by selected chemokines using transwell method into migrated/unmigrated hPDLSCs. The characteristics of the hPDLSC subpopulation recruited by each chemokine were assessed, and gene expression pattern was analyzed by microarray. RESULTS: Chemokines were categorized into three groups by specific patterns of "appearing," "increasing," and "decreasing/disappearing" from healthy to inflamed tissues. A representative chemokine from each group enhanced the capacities for colony formation and osteogenic/adipogenic differentiation while maintaining the surface markers of hPDLSCs. RANTES/CCL5 significantly increased the cellular migration of hPDLSCs, via enhancement of signaling pathways, regulation of the actin skeleton, and focal adhesion. CONCLUSION: The present study found a specific chemokine profile induced by inflammation in periodontal tissues, with RANTES/CCL5 appearing to play a role in the migration of hPDLSCs into inflammatory periodontal lesions.

In Vivo Evaluation of Commercially Available Gel-Type Polyethylene Glycol Membrane for Carrier of Recombinant Human Bone Morphogenetic Protein-2.

PURPOSE: This study evaluated a commercially available, 3-dimensional gel-type polyethylene glycol (PEG) membrane as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) using a rat calvarial defect model. Another gel-type carrier, fibrin-fibronectin system (FFS), was used as a positive control. MATERIALS AND METHODS: Critical-size defects were made in the rat calvarium, which were allocated to 1 of 10 groups comprising 2 healing periods and biomaterial conditions: 1) sham control, 2) FFS only, 3) FFS plus BMP-2, 4) PEG only, and 5) PEG plus BMP-2. Radiographic and histologic analyses were performed at 2 and 8 weeks after surgery. RESULTS: After 2 weeks, some parts of the FFS were biodegraded and extensive cellular infiltration was observed at sites that received FFS or FFS plus BMP-2. The PEG membrane retained its augmented volume without cellular infiltration at sites that received PEG or PEG plus BMP-2. After 8 weeks, the FFS was completely degraded and replaced by new bone and connective tissues. In contrast, the volume of residual PEG was similar to that at 2 weeks, with slight cellular infiltration. In particular, there was progressive bone regeneration around micro-cracks and resorbed outer surface in the PEG + BMP-2 group. Although the PEG + BMP-2 group showed increased area and percentage of new bone, there was no statistical relevance after 2 and 8 weeks in histomorphometric analyses. However, the appearance of the healing differed (with new bone formation along micro-cracks in the PEG + BMP-2 group), and further studies with longer healing periods are needed to draw conclusions about clinical applications. CONCLUSION: Evidence of mechanical stability and new bone formation along micro-cracks when using PEG plus BMP-2 might support the PEG membrane as a candidate carrier material for rhBMP-2.

Ridge regeneration of damaged extraction sockets using rhBMP-2: an experimental study in canine.

OBJECTIVES: This study evaluated the dimensional ridge alteration in a buccal-bone-deficient extraction socket, and ridge regeneration following socket grafting accompanied by recombinant human bone morphogenetic protein 2 (rhBMP-2) or a collagen membrane covering. MATERIAL AND METHODS: In five beagle dogs, entire buccal bone of the extracted sockets of premolars was surgically removed and immediately grafted using one of the following graft protocols: (1) sham surgery without any grafting, and grafting with (2) deproteinized bovine bone mineral (DBBM), (3) DBBM/rhBMP-2 and (4) DBBM covered with a collagen membrane (DBBM/Membrane). Quantitative/qualitative analyses were performed radiographically/histologically after 8 weeks. RESULTS: Buccal-deficient extraction sockets healed with significant reduction in buccolingual dimension along the entire length of the socket, but all grafting techniques reduced the dimensional changes compared to the non-grafted control sites. Histologically, sites received DBBM only exhibited minimal regeneration, whereas sites grafted with DBBM/rhBMP-2 or DBBM/Membrane exhibited greater new bone formation extending the entire augmented area. CONCLUSIONS: Buccal-bone-deficiency may lead to significant volume reduction after tooth extraction along the entire length of the socket, and socket grafting accompanied by rhBMP-2 or covered with a membrane can be candidate therapies for preservation of the buccolingual dimension and successful ridge regeneration.

Apatite-coated collagen sponge for the delivery of bone morphogenetic protein-2 in rabbit posterolateral lumbar fusion.

Bone morphogenetic proteins (BMPs) need an effective delivery system for efficient bone regeneration. In this study, we evaluated the efficiency of an apatite-coated collagen sponge for the long-term delivery of BMP-2 in a rabbit model of lumbar posterolateral fusion. A total of 15 rabbits, divided into three groups, underwent posterolateral lumbar fusion. The first group (control group) received uncoated collagen sponges without BMP-2. The second group (uncoated group) received uncoated collagen sponges with BMP-2 (40 µg each side). The third group (apatite-coated group) received apatite-coated collagen sponges with the same level of BMPs (40 µg each side). All rabbits were euthanized 6 weeks after operation, and the fusion status was assessed by radiographic study, micro-CT, manual palpation, biomechanical study, and histological examination. Fusion rates as determined by radiographic study, micro-CT, and manual palpation showed that the apatite-coated group had a significantly higher rate of fusion than the control group (P = 0.024), while the uncoated group did not (P = 0.083). Biomechanical study showed significantly higher tensile strength in the apatite-coated group than the uncoated group (P = 0.032). Denser trabeculations were found in the apatite-coated group compared with the uncoated group. It is concluded that the use of apatite-coated collagen sponges for BMP-2 delivery enhanced bone regeneration.

Influence of nanocoated calcium phosphate on two different types of implant surfaces in different bone environment: an animal study.

OBJECTIVE: The purpose of this study was to evaluate the osseointegration of two different types of surfaces, smooth and roughened surface implants nanocoated with calcium phosphate (CAP) around different bone environment. MATERIALS AND METHODS: Five male mongrel dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, implants were submerged on both sides of the mandible. On the left, CAP nanocoated roughened surface (RCAP) implants were installed whereas, the CAP nanocoated smooth surface (SCAP) implants were installed on the right side. The control group had no defect, on the other hand, three-wall intrabony defects were surgically created adjacent to the implant in the experimental group. The dogs were sacrificed after 12 weeks. RESULTS: Histological and histomorphometrical analysis were performed with the specimen. The SCAP and RCAP implants showed good osseointegration with no statistical significance in the control group. Histologically, the SCAP group showed little resolution of the defect compared with the RCAP group. In the experimental groups, there was a significant difference in defect fill between SCAP and RCAP. CONCLUSION: Within the limits of our study, it can be concluded that SCAP and RCAP implants show no difference in sufficient bone area whereas, CAP nanocoating on roughened implant surface may enhance osseointegration in deficient bone environment.

Long-term retrospective study of narrow implants for fixed dental prostheses.

OBJECTIVE: The objectives of this study were to analyze retrospectively the long-term survival and success rates of Narrow implants (NIs) placed with various implant systems, and the association with biological and technical complications. MATERIAL AND METHODS: In total, 338 patients (men = 45.6%, women = 54.4%) who received 541 NIs (≤3.5 mm in diameter) for fixed prostheses were enrolled in this retrospective study. The mean marginal bone level (MMBL) change was calculated. Life table analysis with the cumulative survival rate and success rate was calculated, and biological and technical complications were evaluated. RESULTS: The annual MMBL change was 0.07 ± 0.20 mm. The 12-year cumulative survival (success) rates of NIs were 98.1% (91.8%) and 98.5% (93.8%) for the implant- and subject-based analysis, respectively. During the observation period up to 12 years (mean 4.9 years), six implants were lost in the maxilla, whereas three implants were lost in the mandible. Technical complications were more frequent than biological complications. Infection was the most common underlying cause of biological complications and the most frequent technical complication was decementation. CONCLUSION: In conclusion, the findings of this study suggest that NIs could be used safely for narrow alveolar ridges or narrow mesiodistal spaces on the basis of their high survival rate.

Controlled delivery of low-dose bone morphogenetic protein-2 using heparin-conjugated fibrin in the posterolateral lumbar fusion of rabbits.

The heparin-conjugated fibrin (HCF) system has been developed to deliver bone morphogenetic proteins (BMPs) for a long-term period and thus enhance bone regeneration. In the present study, we tested the effectiveness of the delivery system for spinal fusion with a very low dose of BMP-2. A total of 15 rabbits underwent posterolateral lumbar spine, divided into three groups. The control group received only collagen sponges without BMP-2, another group (BMP-only group) received collagen sponges loaded with BMP-2 (10 µg each side), and the last group (BMP/HCF group) received collagen sponges filled with HCF loaded with BMP-2 (10 µg each side). All animals were euthanized 8 weeks after surgery, and the fusion was assessed by radiographs, manual palpation, computed tomography scan, and mechanical testing. No case in the BMP/HCF group or in the control group achieved solid fusion, while all cases in BMP-only group showed evidence of solid fusion. BMP/HCF group had significantly lower fusion rate and tensile strength than BMP-only group at the dose of 10 µg of BMP-2. The HCF long-term delivery system with the low dose of BMP-2 (10 µg) is ineffective for the induction of lumbar posterolateral fusion in the rabbits.

Comparing the clinical effects of local administration of minocycline ointment and doxycycline solution in the treatment of acute periodontal abscesses: a retrospective clinical study.

PURPOSE: The objective of this retrospective clinical study was to provide evidence supporting the adjunctive local application of doxycycline solution or minocycline ointment, in conjunction with drainage, for the treatment of acute periodontal abscesses. METHODS: The study included 63 patients who had received treatment for acute periodontal abscesses through drainage supplemented with 1 of 3 types of adjunctive medications during their initial visit (visit 1; baseline): 1) saline irrigation (the control group), 2) 2% minocycline ointment (the TM group), or 3) 300 mg/mL doxycycline irrigation (the TD group). The same adjunctive medication was administered at visit 2, which took place 1 week after visit 1. Probing depth (PD), bleeding on probing (BOP), plaque index, gingival recession, clinical attachment level, and tooth mobility were clinically evaluated at visits 1, 2, and a third visit (visit 3; 4 weeks after visit 1). Statistical significance was considered to be indicated by P values <0.05. RESULTS: By visit 3, all clinical indices and tooth mobility had significantly decreased in each group. At this visit, PD and BOP on the abscess side were significantly lower in the TM and TD groups compared to the control group. The TD group showed a significantly greater improvement than the TM group, with mean PD reductions of 1.09 mm in the control group, 1.88 mm in the TM group, and 2.88 mm in the TD group. Similarly, mean BOP reductions were 45% in the control group, 73.02% in the TM group, and 95.45% in the TD group. CONCLUSIONS: Local and adjunctive administration of doxycycline and minocycline in combination with drainage exhibited clinical advantages over drainage alone in improving PD and BOP. Notably, a doxycycline solution of 300 mg/mL was more effective than a 2% minocycline ointment.

The clinical effect of locally delivered minocycline in association with flap surgery for the treatment of chronic severe periodontitis: a split-mouth design.

OBJECTIVE: The purpose of this study was to determine the effectiveness of adjunctive application of locally delivered minocycline ointment associated with flap surgery for the treatment of patients with chronic severe periodontitis. MATERIAL AND METHODS: Twenty patients with chronic severe periodontitis were treated in a split-mouth study to either adjunctive application of locally delivered minocycline ointment in association with flap surgery (FM) or flap surgery only (FO); additional minocycline application was performed at 3 months post operation. Clinical evaluation of the plaque index, probing depth (PD), bleeding on probing (BOP), gingival recession, and clinical attachment level (CAL) was conducted at baseline and at 3 and 6 months after treatment. RESULTS: Clinical evaluations revealed that although both sites exhibited clinical improvement, there was a statistically significant reduction in PD (3.34 ± 0.03 mm) and BOP (78.01 ± 11.42%), and a significant gain of CAL (1.88 ± 0.21 mm) at the FM site compared with the FO site (reduction of PD and BOP: 2.62 ± 0.06 mm, 50.33 ± 15.01%, and gain of CAL: 1.55 ± 0.13 mm) at 6 months post operation (p < 0.05). CONCLUSION: Adjunctive application of locally delivered minocycline may be beneficial to the surgical treatment protocol of chronic severe periodontitis.

Acquisition of human alveolar bone-derived stromal cells using minimally irrigated implant osteotomy: in vitro and in vivo evaluations.

OBJECTIVES: Implant osteotomy yields a substantial amount of bone in the form of bone chips entrapped within drill flutes, and can provide a promising cell source for tissue engineering. The aims of this study were to isolate human alveolar bone-derived stromal cells (hABCs) obtained during implant osteotomy, and to evaluate osteogenic differentiation capacity of hABCs. MATERIAL AND METHODS: Bone chips were obtained by minimally irrigated implant drilling technique from 10 human donors. Isolated cells were studied with respect to their colony-forming efficiency, surface marker expression by immunofluorescence staining, fluorescence-activated cell sorting analysis and self-renewal potency. To verify the differentiation activity, in vitro osteogenic and adipogenic gene expressions were evaluated by reverse transcription-polymerase chain reaction, and in vitro formation of mineralized nodule and adipocytes was also evaluated. In vivo bone-forming activity was assessed by ectopic transplantation in immunocompromised mice (n = 5). RESULTS: Human alveolar bone-derived stromal cells population with characteristics of mesenchymal stem cells was present in the isolated cells. Upon hABC transplantation, significant ectopic bone formation was induced with the characteristics of fully matured bone tissue. CONCLUSION: The data support the feasibility of using hABCs as a source of stem cells for dentoalveolar bone tissue reconstruction. The cell source has an advantage that the hABCs can be easily acquired during implant surgery.

Maturation of alveolar bone following implantation of an rhGDF-5/PLGA composite into 1-wall intra-bony defects in dogs: 24-week histometric observations.

OBJECTIVE: The aim of this study was to evaluate long-term (24 weeks) alveolar bone maturation following surgical application of recombinant human growth/differentiation factor-5 (rhGDF-5) in an injectable poly-lactide-co-glycolide-acid (PLGA) composite carrier using an established periodontal defect model. METHODS: Routine, bilateral, 4 × 5 mm (width × depth), 1-wall, critical-size, intra-bony periodontal defects were surgically created at the 2nd and 4th mandibular premolar teeth in 10 Beagle dogs. The animals were randomized to receive (split-mouth design; defect sites in the same jaw quadrant getting the same treatment) rhGDF-5/PLGA high dose (188 µg/defect) versus sham-surgery control (5 animals), and rhGDF-5/PLGA low dose (37 µg/defect) versus carrier control (5 animals). The animals were euthanized for histometric analysis following a 24-week healing interval. RESULTS: Clinical healing was uneventful. The rhGDF-5 high dose significantly increased bone formation compared with controls in terms of bone area (p < 0.05), and a high degree of bone maturation was observed in the rhGDF-5/PLGA high dose group. Root resorption/ankylosis or other aberrant healing events were not observed. CONCLUSION: The rhGDF-5/PLGA appears to support alveolar bone healing/regeneration and the rhGDF-5/PLGA high dose uniquely increased maturation of the regenerated bone.

Sinus augmentation using absorbable collagen sponge loaded with Escherichia coli-expressed recombinant human bone morphogenetic protein 2 in a standardized rabbit sinus model: a radiographic and histologic analysis.

OBJECTIVES: The purpose of this pilot study was to determine the osteoinductive effect of absorbable collagen sponge (ACS) loaded with Escherichia coli-expressed recombinant human bone morphogenetic protein 2 (ErhBMP-2) and evaluate structural stability of ACS in a standardized rabbit sinus model. MATERIAL AND METHODS: The maxillary sinuses were prepared bilaterally in six male white rabbits. The windows were prepared using a 6 mm trephine bur, and circular bony windows were carefully removed. Following reflection of the sinus membrane, a saline-soaked ACS alone and an ErhBMP-2-loaded ACS were inserted into the left and right maxillary sinuses, respectively. After a healing period of 8 weeks, sections of the augmented sinus and surrounding bone were made and analyzed by microcomputed tomography and histologically for signs of window closure and bone augmentation. RESULTS: Radiographic analysis revealed new bone formation in both groups of augmented sinus (i.e., with and without ErhBMP-2). The maximum augmented height did not differ significantly between the groups; however, window closure was significantly more advanced in the ErhBMP-2 group than in the control group (P=0.02). The defect was significantly deeper in the control group than in the ErhBMP-2-treated group (P=0.02). CONCLUSIONS: In conclusion, ErhBMP-2-loaded ACS showed enhanced osteoinductive potential, particularly with regard to bone closure of a sinus window and facilitated maturation of the newly formed bone within the rabbit sinus cavity. However, the structural durability of ACS was not sufficient to maintain the augmented volume in the sinus.

Flap extension attained by vertical and periosteal-releasing incisions: a prospective cohort study.

OBJECTIVES: To evaluate the effect of vertical and periosteal-releasing incisions (PRI) on the extension of the buccal flap in a trapezoidal flap design. MATERIAL AND METHODS: Thirty patients scheduled for implant surgery accompanied by bone augmentation were recruited. The amount of flap extension pulled with a minimal tension of 5 g using a dynamometer was measured before and after the first and the second vertical incisions (VI) and PRI. The results were compared based on gender, surgical site and operator's experience. RESULTS: The first VI extended flap length by 1.1 ± 0.6 mm, 113.4% more compared with the original flap length. The second VI increased flap length by 1.9 ± 1 mm (124.2%), and the PRI significantly extended flap length by 5.5 ± 1.5 mm (171.3%) (P<0.001). The length of the first and the second VI and the amount of flap extension by each incision were compared, and there were no statistically significant differences between gender, surgical site (maxilla vs. mandible) and operator's experience (faculty vs. residents). CONCLUSION: Vertical and PRI in a trapezoidal flap design can be successfully utilized to attain tension-free primary closure during implant or periodontal surgeries. However, the PRI appears to be the only determinant key factor that can significantly extend the length of the flaps, while host- and operator-related factors might not have any significant effect on such flap extension.

The influence of perforating the autogenous block bone and the recipient bed in dogs. Part II: histologic analysis.

OBJECTIVES: This study histologically evaluated the influence of cortical perforation of grafted autogenous block bone (ABB) and/or the recipient bed at different healing periods in dogs. MATERIAL AND METHODS: Four ABBs harvested from the posterior mandible were bilaterally fixed onto the maxillary premolar region in five mongrel dogs. The experiments involved four groups according to the perforation site: the ABB and/or the recipient bed. The animals were killed at 1, 4, and 10 days (early healing periods) and 4 and 8 weeks (late healing periods) postoperatively. Specimens were prepared for histological evaluation. RESULTS: In the perforated ABB groups, blood clots had reached the inner surface of the ABB through a surgically prepared pathway, indicating that revascularization had taken place earlier than in the solid ABB groups. Finger-like bony projections into the graft were observed at the interfaces between the ABB and the recipient bed at the fourth week in all four groups. The remodeling process was observed over the entire ABB in the perforated ABB groups, whereas in the solid ABB groups it occurred only at the interface, and the ABB maintained its original lamella structure with more osteoclastic activity. Interestingly, in the perforated ABB groups, additional new bone with a smooth margin was formed above the block bone's original border. CONCLUSION: It was conjectured that intentional cortical perforation of the recipient bed and the ABB might enhance the initial angiogenesis and the integration of the graft.